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Wasp queens active now

Jeffrey Hahn, Extension Entomologist

Jeff Hahn, University of Minnesota

Photo 1: Yellowjacket queens are occasionally found indoors during early spring

Now that spring has finally arrived, much to our relief, we may need to deal with insects that have been overwintering within our homes. This includes yellowjackets (Vespula spp. and Paravespula spp.) and paper wasps (Polistes spp.). Once freezing temperatures arrived last fall, the old queen and all the workers in nests died. The only survivors were the queens that were produced during late summer.

After these new queens mated, they left their nests and started looking for sheltered, protected sites to spend the winter, much like boxelder bugs or lady beetles. These sites include firewood, loose bark on trees and logs, brick piles, under leaves, as well as in and around buildings. The wasp queens remain inactive until it starts to warm up during late winter and early spring. When queens overwinter in homes, they can also become active when mild temperatures occur during mid-winter.

Jeff Hahn, University of Minnesota

Photo 2: Many paper wasp queen can sometimes be found in homes during early spring

Once active, wasp queens leave their overwintering sites and start to look for an appropriate place to begin a new nest. If they are in buildings, they usually become trapped. Finding wasp queens in homes and other buildings during early spring does not mean a nest is present. While only one or two yellowjacket queens at normally seen at a time, it is possible to see a larger number of paper wasp queens as they like to overwinter gregariously, i.e. in non-social groups.

Physical removal is the only necessary control for wasp queens found indoors. They are just a nuisance and do not indicate a bigger problem. Use a jar or some sort of container to remove and release them outside. If they are by a window or door, just open it up and let them fly out. Killing and removing queens is also an option. This is a temporary problem that will go away on its own.

P1230029.JPGIn 2013, our Legislature directed the Minnesota Department of Agriculture to develop BMPS - "best management practices" - for protecting insect pollinators - bees, moths, wasps, butterflies, etc. The MDA has published the Pollinator Report: Pollinator Bank, Habitat Protection and Pesticide Special Review. I am still reading it. Thought you all might like to as well.

As noted in the Executive Summary (pg. 4), the objectives of the report are: "(i) provide interpretations of the term 'pollinator bank' and propose feasibility, constraints, and uncertainties of the various interpretations; (ii) delineate past, present, and future efforts by MDA, DNR, UMN, MPCA, BWSR and MnDOT to create and enhance insect (native and commercial) pollinator nesting and foraging habitat, as well as to establish and protect pollinator reserves or refuge areas by using Best Management Practices (BMPs); (iii) discuss efforts and progress on developing BMPs to establish, enhance, protect, and restore pollinator habitat that will ultimately be incorporated into pesticide applicator and inspector training; (iv) outline the process and criteria of a special review of neonicotinoid insecticides, and provide a status update on the process, criteria, and progress of the special review of neonicotinoid pesticides registered by the Commissioner for use in this state currently and in the future."

Feel free to pass it on!

Snow fleas are conspicuous but harmless

Jeff Hahn, Extension Entomologist

Jeff Hahn, University of Minnesota

Photo 1: Snow fleas during late winter.

As temperatures warm and snow melts during later winter, a curious insect is sometimes observed. Snow fleas (Hypogastrura nivicola) are small (about 1/10th inch long). But because they are black and typically congregate in large numbers, they are very conspicuous against the white background of snow. From causal observation, snow fleas can look like black pepper. Additionally, they jump which helps to correctly identify them. Watch for snow fleas especially around the base of trees.

Their ability to jump leads some people to believe that these insects are true fleas. However despite its name, a snow flea is a type of springtail and does not bite people. Springtails are wingless and move by walking and jumping. They are very abundant although people usually don't notice them (except of course for snow fleas). They are often found in leaf litter and in the soil where they feed on decaying organic material, fungi, and pollen.

If you find springtails in your yard, just ignore them. They do not damage plants and are harmless to people. They are a curiosity that will go away on their own.

Karl Foord - Extension Educator, Horticulture

I have a Meyer lemon (Citrus × meyeri) which goes outside in the summer and struggles through the long Minnesota winter. This is a wonderful plant with fragrant blossoms and nice fruit. I noticed a lot of very small white cottony blobs on the stems and leaves as well as some scale insects. I believe I have California red scale (Aonidiella aurantii). According to Whitney Cranshaw in his Garden Insects of North America this scale affects many ornamental plants and can be a serious pest of citrus. The adult females are round, reddish orange, and have concentric rings on the cover. Young stages produce some cottony filaments of wax around their body; later stages form the more solid cover.

This scale insect has a fascinating life cycle that features a sessile female and a winged male (Exhibit 1).

I clipped a citrus leaf and examined it under the dissecting scope. I found a sessile female (photo 1) and when I turned her over several crawlers exited (photos 2 & 3). I also found
white caps (photos 4 & 5), late first instars (photo 6) and an individual in first molt.

UCANR Publication #21529

Exhibit 1: California red scale (Aonidiella aurantii) life cycle from

Karl Foord

Photo 1: California red scale (Aonidiella aurantii) sessile female

Karl Foord

Photo 2: California red scale (Aonidiella aurantii) overturned female with exiting crawler

Karl Foord

Photo 3: California red scale (Aonidiella aurantii) overturned female with exiting crawler

Karl Foord

Photo 4: California red scale (Aonidiella aurantii) white cap first instar

Karl Foord

Photo 5: California red scale (Aonidiella aurantii) white cap first instar

Karl Foord

Photo 6: California red scale (Aonidiella aurantii) first instar

Karl Foord

Photo 7: California red scale (Aonidiella aurantii) first molt

Such a lifestyle made me curious as to how such species mate (Exhibit 2).

UCANR Publication #21529

Exhibit 2: California red scale (Aonidiella aurantii) mating

To eliminate the scale, I put the pot in the shower and try to hose off the scale. This knocks them down but does not eliminate them. This is probably an excellent time to consider the use of imidacloprid as a systemic insecticide. The plant is showing some flowers now and no pollinators will have access to these flowers. In addition the material will only be in the pot in a plant holder box in the house and so no chance of contamination of our water systems.

For more information see the excellent publication from the University of California Division of Agriculture and Natural Resources.

Life stages of California red scale

Drugstore beetles: A common stored food pest

Jeffrey Hahn, Extension Entomologist

Jeff Hahn, Univ. of MN

Photo 1: Drugstore beetle

There are a variety of beetles that attack stored food products in our homes. One of the most common is the drugstore beetle. This beetle is 1/10th - 1/8th inch long, dark brown, stout, and oval. Its head is hidden when you look at it from above. With magnification, a series of striations or lines running down its wing covers can be seen. They are able to fly and are attracted to lights.

Drugstore beetles feed on almost anything edible and even a few items that aren't (to people). This includes, but is not limited to, flour and other grain-based products, including bread and breakfast cereals, dried fruits, nuts, and spices, such as dried red pepper, as well as dry pet food. They will also feed on drugs (hence their name), dead insects, hair, leather, paper and books, and horns and antlers. They have even been documented chewing through tin foil, lead sheathing, and wood.

When drugstore beetles are found in a home, the first step in controlling them should be to find out what they are infesting. Because they are able to feed on many items, be sure to make a thorough inspection. Start in the kitchen and check all food items for their presence. However, don't forget about any susceptible items that may be stored in other areas on your home, e.g. pet food. Throw out any infested food material that you find. Keep in mind that there can be more than one infestation source so don't stop looking after you find the first one. For more information on drugstore beetles, see Insect pest of stored foods.

Registration now open for Forest Pest First Detector Workshops

Jeff Hahn, Extension Entomologist

Jeff Hahn, University of Minnesota

Photo 1: Attendees at a Forest Pest First Detector workshop

Are you tree care professional or a forester? Are you a Master Gardener, Master Naturalist, Tree Care Advisor or other Master Volunteer interested in trees? If so and you would like to learn about early detection forest pests like emerald ash borer, gypsy moth, Asian longerhorned beetle, thousand cankers disease, Oriental bittersweet and other pests of special concern, please consider attending a Forest Pest First Detector workshops.

Workshop information can be found here; register early, registration is limited. Please note our first of six workshops will be on Wednesday, February 19 at the MN Arboretum. Our last workshop will be at the Woodland Owner Conference in Rochester on Arbor Day. Also, if you'd like to register to take the Tree Inspector Exam you MUST preregister (a choice on the Forest Pest First Detector workshop form) to take it after the workshop.

SAF and ISA credits and Tree Inspector recertification will be offered. After the workshop we will also offer the Tree Inspector exam for those that preregistered for the exam.

Stay warm,
The Forest Pest First Detector team

Cold snap is no snow day for emerald ash borer management

Rob Venette, Lindsey Christianson and Mark Abrahamson


  • Emerald ash borer (EAB) causes problems when it becomes very abundant in an area. Populations grow slowly until they reach a "tipping point" after which they can grow very rapidly - killing many trees in a short time (1-3 years).
  • We have found that some EAB larvae begin to freeze and die at around -20 F and that survival is very unlikely when temperatures reach below  -30 F.
  • In areas where the coldest winter temperature is generally warmer than -20°F, cold mortality is unlikely to have much or any impact on the population increase of EAB.
  • Rob Venette - USDA Forest Service

    Photo 1: Hypothetical example of EAB population increase to illustrate the possible effects of yearly 60% mortality and 90% mortality

    In areas where the coldest winter temperature is generally between -20°F and -30°F, cold mortality may delay the increase of EAB to levels that kill trees, but EAB should still be expected to reach tree-killing levels.
  • In areas where the coldest winter temperature is generally colder than -30F, cold mortality may have a major impact on population increase of EAB - perhaps to the point of constraining populations below tree-killing levels. We cannot confirm this right now, but we are working to answer this question.
  • We speculate that temperatures within known EAB-infested areas in Minnesota have been cold enough in recent weeks to cause a moderate to high level of larval mortality. This winter mortality should slow EAB population growth in these areas but it is probably not enough to justify changing management plans. EAB populations will likely recover and should still be expected to grow to tree-killing levels. 

Recent media reports have described the potential impact of extreme cold weather on emerald ash borer.  Data collected by us from the winters of 2009-2012 indicate that a substantial fraction of emerald ash borer larvae may die as temperatures fall below -20°F. At that temperature, mortality should be about 50%. Mortality rates increase quickly to about 90% as temperatures approach -30°F. Recent cold temperatures were unlikely to eliminate emerald ash borer populations.  In most cases, the cold has simply set the populations back.  Without additional, severe periods of cold, emerald ash borer populations would be expected to rebound to current densities in a generation or less (<1 to 2 years); however, this brief population setback provides additional time for communities to develop or implement plans for ash borer management.

EAB is a problem because of their potential for rapid population growth and resulting tree mortality. When EAB invades an area there is a characteristic lag period where populations are too small to kill trees and typically too small to detect. However, EAB populations eventually grow to a "tipping point" where population growth accelerates and tree mortality occurs rapidly. Winter mortality of larvae would help to slow population growth and consequently the rate of tree mortality. However, unless winter mortality is consistently very high, EAB populations should still be expected to reach tree-killing levels, albeit more slowly than in areas where no winter mortality occurs.

For these reasons, the authors are not advising any short-term changes to the implementation of municipal or state plans to manage emerald ash borer.  Forecasts of emerald ash borer mortality need to be confirmed with independent observations. 

Impact of cold weather on insects

Jeffrey Hahn, Extension Entomologist

Jeff Hahn, Univ. of MN Ext.

Photo 1: Boxelder bugs aggregate into clusters and use supercooling to protect themselves from extreme cold

With the intense cold weather we have recently experienced, a natural question to ask is what effect this will have on insects.  While the optimistic amongst us are hoping that it will wipe them out, especially the types we like the least like boxelder bugs and mosquitoes, the truth is it will probably have a minimal effect on most insects, especially our native species.

Like their human counterparts, native insects have lived in Minnesota a long time and know how to survive during the winter, even in extreme weather conditions.  That is not to say that some insects won't die as a result of temperatures around -20o F or colder, but most will live to see spring.  So how do they do that?  Insects have several strategies for surviving cold.  These options were nicely outlined in the fact sheet Tough Buggers: Insect strategies to survive winter in Minnesota by Cira,

First, insects survive by avoiding the cold.  This could be like boxelder bugs that find shelter in large numbers under the bark of a dead tree or in our homes.  Some insects, like monarchs, leave Minnesota, migrating to warmer weather for the winter.

Second, they can avoid freezing.  Insects can go through a process call supercooling, i.e. adding a chemical similar to antifreeze into their blood (hemolymph).  This lowers the temperature water will freeze and helps keep their body fluids liquid.  This is a common method for many insects in Minnesota to protect themselves from extreme cold temperatures.  Forest tent caterpillar, a native insect, supercools to protect itself during winter.

Jeff Hahn, Univ. of MN Ext.

Photo 2: Woollybear caterpillars can seek shelter and alter their blood to tolerate freezing

Third, some insects can tolerate freezing.  These insects can release proteins into their blood to help control where, when, and how much ice forms.  By controlling how their bodies freeze, insects can minimize damage to their tissues.  Woollybear caterpillar is an example of a freeze tolerant insect.

It is not unusual for an insect to use more than one strategy for surviving winter weather.  Multicolored Asian lady beetles seek sheltered sites as well as using supercooling.  Of course, some insects do not even survive our Minnesota winters.  Insects, such as aster leafhopper and striped cucumber beetle, migrate into the state from the south during the growing season but are not able to survive our winters.

Cold weather-loving cockroach discovered in U.S.

Jeffrey Hahn, Extension Entomologist

Lyle Buss, University of Florida

Photo 1: Japanese cockroach, male (left) and female (right)

Earlier this month, the Japanese cockroach, Periplaneta japonica, was confirmed for the first time in the U.S. in New York City.  This cockroach is originally from Japan and other parts of Asia.  Although it is not known how this cockroach arrived in the U.S., it is possible that it may have been transported in the soil of ornamental plants. 

This cockroach is fairly large, growing up to 1 3/8th inch long.  It is generally brownish black to black in color.  The male has wings which just extend past the end of its abdomen while the wings of the female cover only about half of its body.  The Japanese cockroach is closely related to the American cockroach, P. americana, a long time pest of the U.S.

The Japanese cockroach can live inside buildings like other pest cockroaches.  What is unusual about this species is that it is tolerant of cold weather; they have been observed outdoors in below freezing temperatures and on snow.  The pest cockroaches that live in the U.S. generally remain indoors in the northern U.S. and are normally not seen outdoors.

What does this mean for the U.S. and Minnesota?  It is not clear how well the Japanese cockroach can spread in here; it has similar habits to other structure-infesting cockroaches and it will probably be challenging for it to become too abundant as it competes for favorable harborages and food.  However, it would not be unexpected for New Yorkers to see this species occasionally outdoors this winter.  Like other cockroaches, the Japanese cockroach is a good hitchhiker so it is possible that it could one day be found in Minnesota.

For more information, see the Entomological Society of American (ESA) news release.

Do-it-yourself bed bug control: What does and doesn't work

Jeffrey Hahn, Extension Entomologist

Jeff Hahn, University of Minnesota

Photo 1: Bed bugs are a serious insect problem today.

After an absence that lasted for decades, bed bugs have become a significant pest problem in our lives again.  Unfortunately, they are usually very challenging and costly to control.  Still, the most effective solution to eliminate them is hiring a pest management company to treat them; they have the experience and understanding of bed bugs to effectively control them.

However, residents can become frustrated with controlling bed bugs (and its cost) and may resort to a variety of do-it-yourself solutions.  Unfortunately, many of these methods are not only ineffective but can make the problem worse and be potentially harmful to people and pets.

The following is a list of what research has shown to be effective and ineffective in bed bugs control.

What does not work?

  • Insecticides purchased in hardware stores, retail variety stores, grocery stores, pharmacies, and other places that sell insecticides to the public.  The active ingredients in the products are not effective against bed bugs.  This can lead people to use insecticides excessively and even apply insecticides that are not labeled for indoor use, such as landscape and garden insecticides which can be harmful to people and pets.  Using ineffective insecticides can also cause bed bugs to disperse, making them more difficult to eliminate. 
  • Bug bombs or foggers (also called total release insecticides).  These products contain ineffective insecticides which does not reach bed bug hiding places when they are activated.  Excessive use of bug bombs can potentially cause explosions and fires and cause severe damage to buildings.  See also the December, 2012 Yard and Garden News for more information,
  • Moth balls.  They have very little effect, if any, on bed bugs.  They can be irritating to people's eyes and noses.
  • House cleaning products.  These chemicals are not effective in eliminating a bed bug infestation.  They can cause bed bugs to disperse, making the problem harder to control.
  • Isopropyl alcohol.  A very labor intensive method that can kill some bed bugs but the alcohol has to come in direct contact with them.  The majority of bed bugs will be unaffected.  
  • Ultra sonic repelling devices.  The sound these devices emit does not kill or deter bed bugs.

While working with a pest management service is the most effective means of eliminating bed bugs from a home, there are some effective steps that people can use to help in their battle against bed bugs. 

  • Heat treatment.  Clothes laundered in hot water and/or dried in temperatures hotter than 122° F for 20 minutes will kill all stages of bed bugs. This is typically the medium-high setting.  You can also heat treat curtains and other fabrics, rugs, shoes, backpacks, stuffed animals, toys, and similar objects by drying them for about 30 minutes (for a full load).
  • Cold treatment.  All stages of bed bugs will be killed when infested objects are placed in a freezer at 0oF for four days.
  • Mattress encasements.  They protect mattresses that are bed bug free from becoming re-infested.  Encasements on infested mattresses and box springs trap bed bugs inside them and allowing you to continue to use them.
  • Interceptors.  Bed bug interceptors are placed under bed legs and captures bed bugs that try to climb up or down beds.  It is used primarily as a monitoring tool to help determine whether bed bugs are present (if that is an issue).

For more information, see Let's Beat the Bed Bugs web page.

Karl Foord - Extension Educator, Horticulture

The United States Environmental Protection Agency (EPA) has instructed the manufacturers to change the labels on those chemicals that have been designated as Pollinator Toxic Pesticides (PTP). One educational piece that has been released describes the changes (Exhibit 1). The label will contain a Bee Hazard Icon to alert users that this is a PTP (Exhibit 2).

The old label language for pesticides toxic to bees was as follows:

"For crops in bloom, do not apply this product to target crops or weeds in bloom."

The new language is as follows:

"Do not apply (product) while bees are foraging. Do not apply (product) to plants that are flowering. Only apply after all flower petals have fallen off."

The language is more extensive for commercial users and lists conditions under which one might apply chemicals even though bees are present. The main difference between old and new labels appears to be the last sentence stating that the product cannot be applied until all of the petals have fallen off the plant.


Exhibit 1:EPA Advisory Box


Exhibit 2: Bee Hazard Icon

At least one significant factor motivating the label changes by the EPA was the move by the European Commission to restrict the use of three neonicotinoids (clothianidin, imidacloprid and thiametoxam) within the European Union. This would be for purposes of seed treatment, soil application and foliar treatment on bee attractive plants and cereals. The member states failed to generate a majority either for or against this proposal and so the decision went to the Commission.

As you might expect, there are those who felt that the move by the EPA fell significantly short of what was required to protect pollinators. The science behind this controversy is no doubt complicated. Traditional experimentation involves setting up experiments where all factors but the one under interest are controlled permitting a clear picture of the effects of this one factor. However, under field conditions it is difficult if not impossible to control all factors in this way and one is left to entangle interactions. For example, there is research demonstrating that the interaction between the neonicotinoid imidacloprid and Nosema (a gut fungus causing dysentery) hampered bees ability to sterilize colony and brood food (Alaus et. al. 2010). This effect was not seen in the control or the single imidacloprid or Nosema treatments.

Even though European Union members failed to achieve a majority vote, the commission still chose to restrict use. On the other hand the U.S. EPA chose to modify labeling language and revisit the issue in 2018 when the registration of these chemicals is subject to review.

Both entities had access to the same research findings. The difference in reaction may be a philosophical one. The European Commission took the position of, given the facts the safety of these chemicals needs to be demonstrated before their use will be reinstated. The U.S. EPA took the position perhaps of, given the facts the damage of these materials must be more definitively demonstrated before their use will be restricted.

Given that we live in the U.S. we have inherited the latter philosophy. However, as a gardener I will be keenly aware of the potential impact of neonicotinoids and only use them on non-flowering plants and only under extreme circumstances, if even that.

C. Alaus et. al. Interactions between Nosema microspores and a neonicotinoid weaken honeybees (Apis mellifera). Environmental Microbiology (2010) 12(3), 774-782.

Beauty is The Beast

Karl Foord - Extension Educator, Horticulture

DSC_0012 forest tent caterpillars jeff hahn shopped and sized


When I first saw this image I thought I was looking at a beautiful tapestry.

However, given the fact that Jeff Hahn was showing me a collection of pictures of insects he had assembled for a slide show presentation at the Minnesota State Fair, I had to rethink that initial impression. On closer examination one can see the head and hairs of a caterpillar. Nonetheless, what beautiful colors and such an intriguing pattern. So much for the beauty.

The only problem is that when this caterpillar has reached the large numbers characteristic of its cyclic pattern of life, it can defoliate many trees. Thus the beast.

Jeff has a video describing more aspects of the caterpillar that will be aired as part of a virtual conference sponsored by the Minnesota Turf & Grounds Foundation. We will provide a link to this presentation in the next issue of the Y&G News.

Jeff Hahn

Photo 1: Forest Tent Caterpillar (Malacosoma disstria

Laura Maskell -

Photo 2: Forest Tent Caterpillar (Malacosoma disstria

Laura Maskell -

Photo 3: Forest Tent Caterpillar (Malacosoma disstria

Watch out for Yellowjackets!

Jeffrey Hahn, Extension Entomologist

Jeff Hahn

Photo 1: Yellowjacket leaving the entrance of an aerial nest. Note black and yellow coloration

This is the time of year when yellowjacket nests are reaching their maximum size and become conspicuous to residents. Two sites where yellowjackets are most problematic are nests that are in the ground and those that are in hidden voids in buildings. A lot of people have mistakenly identified yellowjackets as bees (perhaps because of all of the recent discussion of bees in the media) and are looking for information on how a yellowjacket nest can be moved and saved. Yellowjackets are not important pollinators and it is not necessary to take extraordinary measures to save them. There are not any services that will remove a yellowjacket nest and relocate it.

Jeff Hahn

Photo 2: Honey bee. Note the brown and black body. Don't confuse honey bees with yellowjackets!

Yellowjackets are about ½ inch long, black and yellow, and with few hairs on their body. While honey bees are a similar size, they are mostly a golden brown with black stripes on their abdomen and hairy. While yellowjackets are very common around structures, honey bees are rarely found around homes. Correct identification of stinging insects is further complicated as many people call yellowjackets and wasps bees. Be sure your insects are correctly identified so you know the correct course of action to take (if a nest found around a home is actually turns out to be a honey bee colony, contact the Minnesota Hobby Beekeepers Association for help in removing them).

When yellowjackets are found nesting in the ground, they are challenging to control as you do not actually see the nest, just the burrow entrance that will lead to it. It is tempting to use an aerosol 'wasp killer'; however the insecticide does not get into the nest and has minimal effect on the yellowjackets flying back and forth.

Jeff Hahn

Photo 3: Ground-nesting yellowjacket nest. You only see the burrow entrance but not the nest itself.

The most effective means of controlling a subterranean nest is with a dust labeled for ground dwelling insects, although there is generally not any product like this available to the public. Another option is to use a liquid insecticide, pouring it into the nest entrance, but this is less effective. If you do attempt control, apply it at the entrance of the nest at night when yellowjackets are less active. Check after a day to see how effective the treatment was and repeat if necessary. If you are not successful yourself, then consider hiring a pest management service to treat the yellowjackets for you.

Yellowjacket nests that are found inside homes in wall voids, attics, concrete blocks, or similar spaces are equally or even more challenging. You cannot see the nest, similar to a subterranean nest, but you can see the workers flying in and out of an opening or crack. A dust labeled for use in homes would ideally be the most effective method but these products are generally not available to the general public.

Photo 4: Hidden yellowjacket nest. This is best left to a pest control service to eliminate.

An aerosol insecticide, while readily available, is not very effective. In fact, sometimes an aerosol spray can cause the yellowjackets to look for another way out, which often leads them to the inside of the home. Also, don't seal the nest opening until you know all of the yellowjackets are dead as you can cause the same reaction. The best method to control hidden nests in buildings is to have a professional pest management company treat the nest.

Ultimately, yellowjackets do not survive the winter. If a nest can be ignored until freezing temperatures arrive, all of the workers and the queen will die. The only survivors are the newly mated queens which have already left the nest. They will seek out sheltered sites in which to overwinter. Next spring, they will start their own nests in different sites (old nests are not reused). 

Cicadas are common now

Jeffrey Hahn, Extension Entomologist

Dan Mullen

Photo 1: Dog day cicada, also called annual cicada.

Many people are noticing cicadas now. Despite their appearance, they are harmless to people and property. An adult cicada is a large, one inch long, stout insect with a green or brown body with black markings. Cicadas have four fly-like wings; the first pair is much longer than their abdomen which they hold tent-like over their bodies. They also have very short antennae.

There are two basic types of cicadas, dog day (also called annual) and periodical cicadas. Dog day cicadas, Tibicen spp., do not have a synchronized life cycle so there are some that emerge every year in Minnesota. Periodical cicadas which do not occur in Minnesota spend 13 or 17 years as a nymph in the ground and then emerge together in tremendously large numbers.

While cicadas are present here from July into September, they are more often heard than seen. They produce a high-pitched sound during the day that resembles a powerline hum. Only the males produce this sound in order to attract females. They produce this hum by vibrating a membrane in an internal air chamber.

Jeff Hahn

Photo 2: Cicada nymph climbing up a tree to prepare for its final molt.

More commonly, people see the immature nymphs. They are dark brown and similar in appearance to the adults except that they lack wings. Some people think they look like beetles (perhaps because of their stout shape and that they lack wings) The nymphs are subterranean during their lives spending four to eight year underground feeding on tree roots.

Once they emerge from the ground, they climb up objects such as trees, posts, fences, and even the sides of buildings to finish their development. When cicada nymphs molt into adults, they leave behind 'cast skins'. Sometimes it is not until these empty shells are closely examined that some people realize that these are no live insects.

Fortunately, cicadas are not harmful or dangerous to people, pets, or property in any stage. While they do feed on trees, they do not cause any noticeable injury. If you see cicadas, just ignore them and they will eventually go away on their own. No control is necessary.

Jeff Hahn

Photo 3: Cicada 'cast skin'.

Redheaded Flea Beetles in the Landscape

Jeffrey Hahn, Extension Entomologist

Linda Treeful

Photo 1: Redheaded flea beetle on turlehead (Chelone). Note the irregular brown patches of feeding damage on the leaves.

The redheaded flea beetle, Systena frontalis, is a native insect to Minnesota. It is small, about 1/8 to a ¼ inch long. It has a shiny black body with an orangish red head and moderate length antennae. Like other flea beetles, its hind legs are enlarged and made for jumping.

Redheaded flea beetles feed on a wide variety of plants, especially agricultural crops such as corn, soybeans, cabbage, and alfalfa as well as many weeds. They are now being found in the landscape and nurseries for seemingly the first time where they have been reported feeding on hydrangea, viburnum, and other shrubs as well as many perennials.

Adults typically hatch in July and August and are active on plants until September.
Their feeding can cause small holes which can create a skeletonized appearance in the leaves. In plants with thicker leaves, they remove irregular patches of leaf tissue which eventually turns brown. We have received reports of these beetles in the landscape in Hennepin, Clay, and Carlton counties although they are undoubtedly in other sites in the state.

These flea beetles typically cause little damage to plants. The injury people see on their shrubs and perennials are generally going to only affect the appearance of them. If it does become desirable to treat redheaded flea beetles, they should be easily managed with most residual insecticides.

Redheaded flea beetles have been particularly abundant this year. It is unclear whether this is an emerging landscape problem or a temporary blip. We would be interested to hear any reports of this insect attacking landscape plants. If you encounter redheaded flea beetles, send an e-mail to the author ( and report what plants it is attacking and the location. Also include a picture if possible.

Genista Broom Moths Return to Minnesota

Jeffrey Hahn, Extension Entomologist

Pam Hartley

Photo 1: Genista broom moth caterpillars on false indigo.

Genista broom moths, Uresiphita reversalis, were found last year for apparently the first time in Minnesota. They fed almost exclusively on false indigo (Baptisia) here. Other plants that they are known to attack include lupines and honeysuckle (Lonicera spp.)

It was thought that their appearance here the result of migrant moths moving into Minnesota, probably with the help of storm fronts. The question was whether they would survive winters in Minnesota and would we see them again next year. It is not clear whether any of them survived our winter but it is clear that they are in Minnesota again in 2013 as reports have been coming in since mid-July. Most of the sightings have been in the Twin Cities area, but this caterpillar has also been spotted west of Minneapolis in McLeod County. Most of the sightings have been on false indigo with one report on lupine.

Interestingly, genista broom moth caterpillars have generally have not been reported in Iowa, although one home gardener spotted them in east central Iowa. They have not been reported in Wisconsin to date.

If you find these caterpillars in your garden and they are about one inch long, you can ignore them as they are essentially done with their feeding. If they are smaller, you have a few options. Probably the easiest thing you can do is to handpick them. It they are numerous, consider a low impact insecticide, such as insecticidal soap, spinosad, or Bacillus thuringiensis.

If you discover this caterpillar in your garden, especially in Minnesota, please contact the author ( and report it. We are trying to determine where these insects have been found and whether they return the following summer.

Karl Foord - Extension Educator, Horticulture

Karl Foord

Photo 1: Flower garden for pollinators

Karl Foord

Photo 2: Great black wasp (Sphex pensylvanicus)

Karl Foord

Photo 3: Great black wasp (Sphex pensylvanicus) on left

Karl Foord

Photo 4: Great black wasp (Sphex pensylvanicus) and golden digger wasp (Sphex ichneumoneus) on Culver's Root (Veronicastrum virginicum)

I am not sure what I expected when I created this pollinator garden (photo 1), but I have certainly gotten a whole new perspective on what happens in a flower garden. I have encountered so many different species that I will create a series of pollinator garden observations. I will begin with wasps and follow up with many types of flies and bees.

The garden has been continually patrolled by a great black wasp (Sphex pensylvanicus). This wasp is perceived as a black streak that weaves its way around the different plants in the garden searching for prey (photos 2 & 3). It only rarely lands to fuel up on nectar at a Culver's Root plant (Veronicastrum virginicum) seen here with a golden digger wasp (Sphex ichneumoneus) (photo 4). It sometimes hassles other residents. I have seen it touch the back of bumblebees who fly in response but are not harmed. It had an encounter with a hummingbird but both went their separate ways.

Karl Foord

Photo 5: bald-faced hornet (Dolichovespula maculata)

I encountered a bald-faced hornet (Dolichovespula maculata) gathering nectar on Summer Beauty Onion (Allium lusitanicum 'Summer Beauty'). It looked to have enough hairs to actually be accomplishing some transfer of pollen.

Karl Foord

Photo 6: Thick-headed Fly (family Conopidae)

Another interesting character was this Thick-headed Fly (family Conopidae) whose thread-waist mimics that of the Sphecid wasps. The thick-headed fly was on Hoary Vervain (Verbena stricta).

Karl Foord

Photo 7: Cuckoo Wasp (Family Chrysididae)

Lastly we have a iridescent well armored Cuckoo wasp (Family Chrysididae) (photo 7). This wasp is parasitic on other wasps, laying its eggs in the already provisioned nests of other wasps.

Karl Foord

Photo 7: Cuckoo Wasp (Family Chrysididae)

A well camouflaged female Goldenrod Crab Spider (Misumena vatia ) was quite tentative around this customer. I have seen crab spiders with captured flower flies and butterflies, but this wasp may have been too well armored to warrant an attack.

Karl Foord

Photo 8: Cuckoo Wasp (Family Chrysididae) and Goldenrod Crab Spider (Misumena vatia)

The other interesting thing is that I am sure there are at least 10 other species of wasps in the garden that I have observed but not yet identified. To be continued...

Editor's note: The primary reference for this article was Jeff Hahn's book Insects of the North Woods. The spider was identified through Larry Weber's book Spiders of the North Woods. Thanks to both of these authors.

Grape pelidnota

Jeffrey Hahn, Extension Entomologist

Grape Pelidnota

Jeff Hahn

Photo 1: Grape pelidnota-- a big scarab beetle

A conspicuous insect has been showing up this summer around people's gardens and homes. A grape pelidnota, Pelidnota punctata, is a type of scarab beetle that looks like a big June beetle. Also known as grapevine beetle, it is a good sized insect measuring about one inch long. It is a rusty orange color with six black spots on its body (two on its thorax and four on its wing covers).

Grape pelidnotas can be found throughout the late spring and summer. Like their name suggests, the adults feed on grapes, although they typically do not cause much damage (just handpick them if they become numerous). The larvae are associated with rotting hardwood tree logs and stumps. The adults are attracted to lights so you can find one around your home even if you don't have grapes. Although they might look imposing, grape pelidnotas are harmless to people and pets. They are just a curiosity and can be ignored.

Spotted wing Drosophila found in Minnesota again

Jeffrey Hahn, Extension Entomologist

One of the bigger garden questions last year was whether we would see spotted wing Drosophila (SWD) again in 2013.  SWD flies are invasive insect pests that damage a variety of thin-skinned fruit crops, such as raspberries, blackberries, strawberries, cherries, plums, blueberries, and grapes.

Jeff Hahn

Photo 1: Female spotted wing Drosophila on blackberry. It lacks the dark spot on its wings that males have.

Unfortunately, the answer is yes.  The University of Minnesota and Minnesota Department of Agriculture (MDA) have detected and confirmed the presence of SWD in Minnesota this year.  The first confirmed report of SWD this year occurred on June 27 when a male SWD was found in a vineyard in Dakota County.  SWD was then verified on July 3 in summer raspberries in Rice County.  There have also been fly specimens suspected to be SWD in several other counties not only in the Twin Cities area but also in Greater Minnesota.  You can go to the MDA web page to check for updated information on where SWD has been found.  Last year, the first SWD was found in August.  Eventually, SWD was confirmed in 29 counties in Minnesota.

SWD looks very similar to the small fruit flies you might see flying around overripe fruit on your kitchen counter.  They are about 1/8th inch long, yellowish brown with red eyes.  The male is fairly easy to identify; look for a dark spot near the tip of the wing.  Unfortunately, the female lacks this spot and is difficult to identify without high magnification.  The larvae are cylindrical in shape, tapering at one end.  They are legless, whitish and very small, no more than 1/8 inch long.  However, if you find fruit fly adults or larvae associated with healthy fruit, there is a very good chance it is SWD; other fruit flies are typically associated with overripe and rotting fruit.

If you have potentially susceptible fruit in your garden, consider putting out vinegar traps to try to detect SWD so you have some warning if they are present in your garden.  If you do find SWD, be sure to harvest ripe fruit frequently.  Remove and dispose of any overripe or rotting fruits.  You can also use insecticides to help protect your fruit.  Target the adults though, as there is not any practical solution one fruit is infested by the larvae.  The only option is to properly destroy the fruit so the flies cannot finish their development.

For more information on SWD management, see the publication Spotted wing Drosophila in home gardens.

If you believe you have SWD, especially in a county where it is not been confirmed, contact the Minnesota Department of Agriculture "Arrest the Pest" hotline by email at or leave a voicemail at 1-888-545-6684. 

Karl Foord - Extension Educator, Horticulture

I just returned from a two week absence from my garden due to training and a vacation, and I was anxious to see how things had progressed.

Karl Foord

Photo 1: Leaf with holes created by leaf-cutter bees

The first thing I saw was an 'Autumn Blaze' maple volunteer on the edge of my sidewalk. Normally this would be simply a weed to pull, BUT in this case the maple leaves told an interesting story. The holes in the leaves were clearly the work of leaf-cutter bees (Megachile spp.) (photo 1). Notice that the holes cut by the bees have two different shapes. One shape is a circle (photo 2) best for plugging nesting holes, and another shape is oblong best for lining nesting holes (photo 3).

Karl Foord

Photo 2: Round holes for plugging tunnels

Karl Foord

Photo 3: Oblong holes for lining tunnels

And sure enough the leaf-cutter bee was found working a flower on Hoary Vervain (Verbena stricta) (photo 4).

Karl Foord

Photo 4: Leaf-cutter bee (Megachile spp.) on Hoary Vervain (Verbena stricta)

Also observed was an Andrenid bee on Birds-foot Trefoil (Lotus corniculatus)

Karl Foord

Photo 5: Andrenid bee on Birds-foot Trefoil (Lotus corniculatus)

Karl Foord

Photo 6: Male Widow Skimmer (Libellula luctuosa)

Karl Foord

Photo 7: Male Widow Skimmer (Libellula luctuosa) perching after having caught prey

Another fascinating creature resident in the pollinator garden was a male Widow Skimmer (Libellula luctuosa) coming in for a landing (photo 6) and perching after having caught prey (photo 7).

The garden continues to provide compelling theatre for the patient and observant. Please enjoy your garden!

Jeffrey Hahn, Extension Entomologist

Jeff Hahn

Photo 1: Spotted wing Drosophila is one of the pests attendees will learn about at the Fruit and Vegetable Pest First Detector workshop.

It is not too late to sign up for the Fruit and Vegetable Pest First Detector Workshop. If you have an interest in fruits and vegetables and want to learn more about new and emerging invasive pests and pathogens that are threatening Minnesota, then consider signing up for this half day program. This workshop, put on by the Minnesota Department of Agriculture (MDA) and the University of Minnesota Extension, is scheduled for Wednesday, July 24 at the MacMillan Auditorium at the Minnesota Landscape Arboretum. Check in starts at 8:00 a.m. and the program begins at 8:30. The workshop ends at noon.

This workshop is appropriate for anyone with an interest in fruit and vegetables, including home gardeners. Attendees will learn how to identify invasive pests and distinguish them from common look a likes. They will also find out the proper steps to take if they suspect you have found and invasive pest.

Attendees have the option to become a First Detector volunteer. First detectors are a local resource to help state officials respond to calls made to the Arrest a Pest Hotline. First Detectors are volunteers trained to help citizens diagnose and report possible infestations of invasive species to the Minnesota Department of Agriculture. First Detectors are a part of the National Plant Diagnostic Network (NPDN) First Detector Program which promotes the early detection of invasive plant pathogens, arthropods, nematodes and weeds.

For more information, see the Minnesota Fruit and Vegetable Pest First Detector web page, . To register, go to the Minnesota Landscape Arboretum web page.

Ready or Not: Here come Japanese beetles!

Jeffrey Hahn, Extension Entomologist

Jeff Hahn

Photo 1: Japanese beetles were first reported in Minnesota this year on July 5.

Japanese beetles have just recently started to emerge; watch for them in your gardens and landscapes. If you find just a handful of these insects, you can easily tolerate any damage they cause. If higher numbers are found, there are steps you can take to protect your plants from them although some damage is likely to occur regardless of what you do.

Jeff Hahn

Photo 2: Japanese beetles that were handpicked off of raspberries

There are a couple of non-chemical methods you can consider. When practical, handpick the Japanese beetles from plants. This is best done early in the morning and late in the evening when Japanese beetles are less active. Have a container of soapy water with you so that beetles that are brushed or picked off the plants can end up in it where they are killed. For smaller plants, consider using a fabric barrier, like cheesecloth, around the plant. Be sure to take the fabric off of any plants that are flowering so bees can reach them.

One non-chemical method to avoid is traps. They have a floral lure attractive to both sexes and a mating pheromone that draws in just male Japanese beetles. Once deployed, traps can catch what appears to be an impressive number of insects. However, in areas where Japanese beetles are common, this is a drop in the bucket compared to what is actually present. Research from the University of Kentucky has shown that these traps actually attract more Japanese beetles than they capture; often plants in the area actually suffer more damage than without the traps.

If you are interested in using an insecticide, consider a low impact product like Neem or pyrethrins (containing PBO). However, these products are generally not very effective against large numbers of Japanese beetles. If you would like to use a product with a longer residual, consider a pyrethroid, such as permethrin, lambda cyhalothrin, or cyfluthrin. Another option is carbaryl (Sevin). Depending on the Japanese beetle numbers, you may need to make more than one application. Be careful not to apply one of these insecticides when bees are active.

Jeff Hahn

Photo 3: Don't use Japanese beetle traps. You will probably draw more beetles into your garden than what you actually catch.

Another option is the use of imidacloprid, a type of systemic insecticide (dinotefuran is a similar systemic insecticide but is less effective against Japanese beetles). It's easy to apply and is long lasting so only one application during the summer is necessary. It does not kill Japanese beetles quickly but it does cause them to stop feeding, then they die a little later. One important drawback of these products is they are very toxic to bees. Avoid treating plants, like linden and honeylocust, which are attractive to bees. It doesn't matter that the plants are not flowering at the time of application as these insecticides will be active up to a year. Another important consideration is that it takes some time for imidacloprid to be translocated in trees, up to three to four weeks for a large tree. You have to think ahead if you want to use this product.

Another option is to have your trees sprayed with chlorantraniliprole (Acelepryn). This insecticide is effective against Japanese beetles, is long lasting and has low impact on bees. It is only available to licensed applicators so you would need to contact a landscape company for this treatment.

While you're dealing with adult Japanese beetles munching on your garden and landscape plants, you might also have to worry about immature grubs in the soil feeding on the roots of turfgrass. If you experienced problems with Japanese beetle grubs last year, you can expect to have problems with them in your lawn again this year. Now is a good time to use a preventative insecticide, just as the adults are starting to become active. By the time eggs are laid and grubs hatch, about two to three weeks, the insecticide will be taken up by the grass and the young grubs will be exposed to it.

Parasitic nematodes, especially Heterorhabditis species, can be an effective, low impact treatment. Apply nematodes late in the evening. It is important that they are watered in and that the soil is kept moist for at least a week (two to three weeks is even better). Nematodes are typically mailed ordered from garden catalogs or biological control companies. Milky spore disease is a common and familiar treatment. However, it isn't very effective against Japanese beetle grubs. There are several traditional preventative insecticide options that are very effective. Look for imidacloprid (various trade names), chlorantraniliprole (Scott's GrubEx), or clothianidin (Green Light Grub Control with Arena).

Jeff Hahn

Photo 4: The smaller Japanese beetle grubs are, the easier they are to kill. By late August they will be too large to kill very easily.

As the grubs get older they are less affected by preventative insecticides. It is still possible to control them with a curative insecticide. Trichlorfon (Dylox) and chlorantraniliprole (Scott's GrubEx) are effective curative insecticides. You can effectively treat Japanese beetles until about mid to late August. By then, the grubs are getting too large to manage very well with any insecticide. Remember to only treat the grubs if you are experiencing problems in your lawn. It is not effective to control grubs to reduce the number of adults that are seeing. Adult beetles are good fliers and can easily fly into your yard from the surrounding neighborhood.

The University of Minnesota Extension and the Minnesota Department of Agriculture are conducting a survey to track where Japanese beetles are found in Minnesota. If you find Japanese beetles, contact Jeff Hahn, to report it. Please include a digital picture when you e-mail your report.

Stag Beetles in Yards

Jeffrey Hahn, Asst. Extension Entomologist

Jeff Hahn

Photo 1: Stag beetles. Note the large mandibles.

People have been finding stag beetles in their yards and gardens recently, sometimes in large numbers. Also known as pinching bugs, these beetles typically measure a little more than one inch in size and are reddish brown to dark brown in color. Stag beetles resemble June beetles but have more prominent heads. The mandibles (jaws) of both sexes are also large and conspicuous, especially those of males. Stag beetles have short antennae with conspicuous asymmetrical plates (lobes) at the end of them which they are not able to close together. One of the most common species in Minnesota is Lucanus placidus.

All stag beetle larvae feed in dead or decaying wood, such as logs and stumps. Most adults emerge in May or June and feed on sap that exudes from plants. Stag beetles are active at night and are often attracted to lights. They can fly into a yard, land on the ground and remain there until the following morning. Some people have observed stag beetles emerging from the ground. This indicates that there are some old roots or other buried decaying wood where the larvae were feeding and developing.

Although a lot of stag beetles in a yard is annoying, they are harmless to people and property. Do not spray stag beetles, their control isn't necessary. Just ignore them until they go away on their own.

Protect Yourself from Mosquitoes

Jeffrey Hahn, Asst. Extension Entomologist

A benefit of our cold, late spring has been that the primary biting mosquito in Minnesota, Aedes vexans, was delayed in its emergence until early June. However, they are out now and if you spend any time outside, they will find you sooner or later. Mosquitoes have been particularly abundant this year because of the frequent rainfalls we have received. As long as we received regular rain, we can expect to continue to battle mosquitoes. In addition to the annoyance of their bites, mosquitoes are capable of transmitting diseases to people, especially west Nile virus (there were 70 cases in 34 counties in Minnesota last year including one death) and Lacrosse encephalitis. 

Jeff Hahn

Photo 1: Mosquitoes are abundant when we have a lot of rain.

It is challenging to completely avoid mosquito bites but there are some steps you can take to minimize your exposure to them. It is important to remove or drain potential breeding sites for mosquitoes. Any kind of standing water, with a little bit of organic material, is a suitable place for mosquito larvae to live and develop. This can include, but not limited to, buckets, tires, cans, and children's' swimming pools. Even clogged gutters can be source for mosquitoes. The key is that the site contains shallow water and is left undisturbed. While this step helps to reduce mosquitoes that can be produced on your property, this does not impact mosquitoes that can fly into your yard from adjacent areas.

Try to avoid, when possible, being outside when mosquitoes are most common. Mosquitoes typically are most active and bite during the morning and evening, although they will take a blood meal from us anytime during the day if we are close enough to their resting sites around grassy and brushy areas, shrubs, and trees.
Also use personal protection to help prevent mosquitoes from biting you. Consider wearing protective clothes to cover bare skin including sleeves shirts, long pants, and socks and shoes. Ultimately, the best personal protection against mosquitoes is the application of repellents.

Photo 2: Using a repellent, like DEET, is the best defense against mosquitoes.

The most effective and long lasting repellent is DEET (N,N diethyl m toluamide). This product has an excellent track record of safety for the last six decades. It comes in different concentrations, ranging from 4% to 100%, offering protection from 90 minutes up to 10 hours. However, there appears to be a limit to how much protection increasing concentrations of DEET can provide. There is evidence that suggests that there may not be much difference between concentrations of 35% and 100%. Applications of no more than 30% DEET can be used on children and infants at least two years old.

There are several alternatives that are effective repellents. One is option is picaridin. Picaridin has long been used as a mosquito repellent in Europe and Australia. It sold in the U.S. as a 7% or 15% concentration (Cutter Advanced and Cutter Advanced Sport). It is comparable to lower concentrations of DEET in effectiveness. Picaridin is generally less irritating to skin and lacks a chemical odor and sticky feel. Do not treat children younger than two years old with this product.

There are a couple of botanically based repellents available. Oil of lemon eucalyptus (p-menthane 3,8-diol), Repel brand, is a plant-based repellent sold as a 40% concentration. It is comparable to products containing low concentrations of DEET. Bite Blocker containing 2% soybean oil is also option. Research has shown that this repellent can offer protect for about 90 minutes or about the same protection as a very low concentration (4.75%) of DEET.

Whatever repellent you choose to use, be sure to always follow all label directions so the product is used most effectively while minimizing potential hazard to safety.

People's frustration with mosquitoes often leads them to put their faith in a variety of dubious methods to combat these blood-sucking insects. However, people are typically disappointed in the results of these tactics. Caveat emptor (buyer beware) -- what sounds too good to be true usually is.

Insect electrocuters, also known as bug zappers, attract large numbers of insects. However, research has shown that mosquitoes makes up less than 5% of all the flying insects killed. The number of mosquito bites remained the same regardless of whether or not you used a bug zapper. Research has even showed that insect electrocuters do more harm by killing beneficial insects.

Mosquito traps use carbon dioxide to attract mosquitoes, but it is unlikely that they can remove enough mosquitos to reduce the incidence of mosquito bites in a given area. While they sometimes can trap an impressive number of mosquitoes, this is a percentage of the overall mosquito population around the traps. Under the right circumstances, these traps can actually draw more mosquitoes into a yard than what they actually collect. These devices are also usually expensive.

Jeff Hahn

Photo 3: Beware of gimmicks that promise to get rid of your mosquitoes; they are unlikely to prevent mosquitoes from biting.

There are a variety of devices that use sound to repel mosquitoes. They may claim to imitate the sound of male mosquitoes or predators like bats or dragonflies, insects or animals that female mosquitoes are supposed to avoid. Unfortunately this doesn't repel them in practice. Research has tested many of these products; none reduce the number of mosquito bites. A female mosquitoes' urge to find a blood meal outweighs potential threats to them.

The Citrosa 'Mosquito Fighter' plant is genetically created by crossing an African geranium with the Grass of China (which contains some citronella, a mild repellent). These plants are pleasant smelling and will grow to a height of 12 feet if left unpruned. But despite their claims, research has demonstrated that these plants do not repel mosquitoes. Citronella candles can help to some degree but its effectiveness is limited to small, calm areas. Any wind will disperse the smoke, negating any effect the candles could have.

Purple martins and bats have been reputed to consume large numbers of mosquitoes. While there is generally nothing wrong with encouraging these animals, mosquitoes actually made up less than 3% of purple martins' diets and less than 1% of bats' diets. Larger-sized, flying insects, such as dragonflies, butterflies, crane flies, beetles, and moths are the most common meals for these animals. The presence of purple martins and bats does not diminish the number of mosquito bites.

Something "bugging" you????? Join Julie Weisenhorn and special guest extension entomologist, P1150490.JPGJeff Hahn, this Saturday, 8-9am, on WCCO Radio's "Smart Gardens" (830 AM on the dial). This is your opportunity to get Jeff's help in solving those pesky pest questions. Listeners can call or text in questions for Jeff and Julie.

About the show: WCCO Radio has teamed up with U of M Extension to bring you "Smart Gardens" which airs every Saturday from 8-9 a.m. If you have something to say, call-in at 651-989-9226 or text 81807. For more info and podcasts: WCCO Smart Gardens

What the Heck is a Hellgrammite?

Jeffrey Hahn, Asst. Extension Entomologist

Andrew Williams

Photo 1: Hellgrammite, the larva of a dobsofly

Some residents have been recently encountering a large (and to some people a scary) insect larva. This dark colored insect, a hellgrammite (Corydalus cornutus), has an elongate and somewhat flattened body. It has six conspicuous legs as well as a series of filaments on the sides of its abdomen with small finger-like gills clustered at the base. A hellgrammite also has very prominent, strong mandibles (jaws). It reaches about two to three inches in length when fully grown. Despite its appearance, hellgrammites are not aggressive or dangerous to people, although it is possible that they can bite if they are handled carelessly.

A hellgrammite lives in running fresh water, such as streams or rivers, often hiding around rocks or debris. They are predaceous, feeding on insects and other aquatic invertebrates. They have the interesting ability of being able to swim backwards as well as forward. It is generally believed that they take one to three years before crawling out onto dry land to finish their development. They will usually create a cell in the soil near the water to pupate. They are sometimes used by fishermen as bait.

John Fogal

Photo 2: Male dobsonfly. Note the large mandibles.

As an adult, a hellgrammite becomes a dobsonfly. A dobsonfly is brown up to two inches long with long slender antennae and long wings with conspicuous mandibles. You can distinguish between the sexes as males possess mandibles up to 3/4 inch long, making them look quite fierce and dangerous. Fortunately they are not able to bite people, using their mandibles only for fighting other male dobsonflies. Females have smaller mandibles but could bite people if given a chance. Although adults are usually found near water, they are attracted to lights and can be found a fair distance away. Dobsonflies are harmless and are just a curiosity.

Pine Sawfly Larvae are out and about

Karl Foord - Extension Educator, Horticulture

Keep and eye out for Pine Sawfly Larvae. Please refer to the following two articles for details.

European Pine Sawfly is Active Now

Sawflies of trees and shrubs

Karl Foord - Extension Educator, Horticulture

Apple maggots are predicted to emerge in the beginning of July so this is a good time to consider protective strategies.

Karl Foord

Photo 1: Apple fruit prior to thinning

Apple maggot flies recognize and identify apples through a series of visual and chemical clues. The red sphere traps and the yellow square traps both covered with a sticky substance as well as scented lures aid in capture of apple maggot flies and will indicate their presence. However, it is unlikely that such traps will effectively protect your apples.

Karl Foord

Photo 2: Apple fruit after thinning

I have tried plastic bags which can work although they make the tree look phantasmagorical (i.e. nightmarish - please forgive - I always wanted to use that word in a sentence). I have also found that they can collect water and if faced toward the south can heat up and cause damage to the apple skin.

Karl Foord

Photo 3: Apple fruit with maggot barrier I

So this year I am trying Maggot Barriers that I purchased from the Seattle Tree Fruit Society although there are other suppliers of this product that can be found on the web. The Seattle Tree Fruit Society web site does show pictures of their recommendations for attaching the barrier. The maggot barriers are the so called "footies" which serve as single use protective socks that can be used to try on shoes if you have no socks.

Karl Foord

Photo 4: Apple fruit with maggot barrier II

The maggot barriers may confuse the flies who no longer recognize the apples because of the different color and texture of the footie covering the apple. The barriers may physically inhibit the maggots from depositing their eggs under the skin of the apple. However, mosquitoes don't seem to have any problem getting their proboscis through our woven shirts, so I wonder if apple maggot flies would really have a problem getting their ovipositor through the mesh of the footie.

Karl Foord

Photo 5: Apple fruit with maggot barrier III

This is the procedure that I am using. First thin the flower to one fruit per cluster (Photos 1 & 2). Then slip the sock/barrier over the apple and secure with a rubber band. I have three examples: the first with the apple at the end of the sock (photo 3), the second with the apple in the middle of the sock (photo 4), and finally the apple with most of the sock above the apple (photo 5). (note the last photo was taken with a flash which is why the color is so different)

I will let you know how this works for me.

For more information on apple maggot including other methods of control please use the following link. apple maggot

Karl Foord - Extension Educator, Horticulture

This spring I noticed the black color on the branches of my Taylor's Sunburst Pine (Pinus contorta 'Taylor's Sunburst'). I remember seeing the same thing on my Uncle Fogy Jack Pine (Pinus banksiana) last year. The cause was the same in both cases Sooty Mold that has formed on the honeydew secretions of the Pine tortoise scale (Toumeyella parvicornis). To confirm this I went to the What's Wrong with My Plant Diagnostic Tool via the Extension Garden web page/Pest Management/Diagnose a Problem link. I tracked through "Evergreen Trees and Shrubs" to "Pine" to Black powdery coating on "needles" and "shoots". This confirmed the Sooty Mold. I also tracked through "Sticky substance coating needles" to confirm the Pine tortoise scale as the culprit.

Karl Foord

Photo 1: Uncle Fogy Pine (Pinus banksiana 'Uncle Fogy'

The scale organism put such stress on my Uncle Fogy Pine that the needles it produced were half the size of the normal needles. Upon removal of the scale the needles returned to normal size (photo 1). I had learned my lesson about the impact of Pine tortoise scale on my trees.

I knew that Imidacloprid had worked on Uncle Fogy so I grabbed the bottle and reread the label - not trusting my memory. I confirmed that yes this product is labeled for soft scales. I also reviewed the precautions about letting the chemical get into aquatic environments - no lakes, streams, or ponds nearby. I agreed with the label that whatever I used to measure the chemical should not be followed by using the same utensil for soup.

There was nothing on the label regarding protective equipment, however the label warned that this chemical can be harmful if absorbed through the skin so I followed my previous procedures of long sleeve shirt, long pants and plastic gloves for handling.

Because this was an evergreen ornamental tree I was not concerned about the potential effects of a systemic pesticide on pollinators because there would be no flowers to pollinate. Also because the product is used as a drench around the plant, I didn't have to worry about airborne spray drifting onto other plants, people, or pets. In addition there were no wet leaf surfaces so there was no issue of reentry to the area or drying time of the product.

The directions called for the tree trunk circumference in inches at a height of 4.5 ft. and that this length in inches should equal the number of ounces of product to be applied to the plant. But there were too many needles to measure the circumference so I estimated the diameter and multiplied by Pi. How often do you get to use the trigonometry you learned in high school? The amount came to @ 5 oz. I added this to a gallon of water as instructed and applied the solution evenly in a circle 2 ft. from the tree trunk. Put the container away and washed up.

I checked the tree every other day or so and several days later the scales were starting to look ill. In approximately two weeks all the scales were dead. My Taylor's Sunburst Pine is looking and growing nicely without having hundreds of Pine tortoise scale stylets sucking its "life's blood" plant sap.

Reading the label wasn't all that painful. Reading size 6 font text definitely required glasses for "mature" eyes. However, I did not skim the label or skip parts. I read carefully and made sure that I understood all parts and the risks involved. Yes following the label is the law. Following the label is also the responsible and intelligent thing to do. By proceeding in this manner I felt in command of the situation and understood that the action I was taking was going to solve the problem with minimal impact to the environment and all the other actors in our theater of life.

Carpenter ants in spring

Jeffrey Hahn, Asst. Extension Entomologist

Jeff Hahn

Photo 1: Carpenter ant worker. Note the one segmented petiole and the evenly round thorax in profile.

Although carpenter ants can be found in homes anytime during the year, they seem particularly noticeable in the spring as the weather becomes warm.  Many people think of carpenter ants as big, black ants.  And it is true the most common species here is black and approaches ½ inch in length.  However, you can't always go by size and color; there is another carpenter ant species that is red and black and about 3/16th inch long.  A more sure method is to look for a one-segmented petiole between the thorax and the abdomen (ants either have a one or two segmented petiole.  Also examine the shape of the thorax (the middle section of the body).  In carpenter ants, the thorax is evenly round in profile while other Minnesota ants have unevenly shaped thoraxes.

Finding carpenter ants inside in the spring can mean that a nest is present there; the sooner they are present indoors with the onset of warm weather, they more likely a nest exists in your home.  Also look for signs of coarse sawdust which is a sign of a nest.  If you find a swarm of winged carpenter ants indoors, that is a sure sign of an indoor nest.  Remember that not all winged ants you see are carpenter ants so be sure they are correctly identified.  If you find just one or several carpenter ant queens (winged or wingless) in your home, they probably just wandered into your home accidentally and no nest is present.

Jeff Hahn

Photo 2: Carpenter ant queen. A swarm of queens inside indicates a nest in the home.

There are two types of carpenter ant nests.  Parent colonies nest in moisture damaged wood while satellites nests, offshoots of the main colony, can nest in sound wood as well as insulation and hollow doors.  Carpenter ants have the potential to damage the wood in buildings as they excavate galleries and tunnels.  Fortunately, this damage occurs relatively slowly and it usually takes years for it to become severe enough to be an issue.

If you believe that you have a carpenter ant nest in your home, it is very challenging to control it yourself.  It is critical to deliver insecticide to the nest; just killing the foraging workers has no impact on the nest.  Typically baits are used for ant problems.  However the ant baits available to the general public  are not sufficiently attractive or effective to successfully eliminate a carpenter ant nest.    

The best control for carpenter ants is to contact a licensed pest management service to treat the nest.  An inspection is very important to find the foraging trails and ideally the nest(s).  There are several options for treating the nest.  Many technicians use a non-repellant residual insecticide (e.g. Termidor), sprayed around the building's exterior.  The carpenter ants pick up residue; take it back it to the nest where it gets spread through colony, ultimately eliminating it.  Technicians may also set out baits to control carpenter ants.  They have a variety of baits and the experience to choose the proper bait that will be most effective (it is not unusual for technicians to use more than one bait to be successful).  Keep in mind that baits take time so it is important to be patient and allow carpenter ants to take back sufficient bait to control the nest.  If the exact location of the nest is discovered, it can be treated directly, especially with a dust.

For additional information, including preventative steps, see the publication, Carpenter ants.

Eastern tent caterpillars are now out!

Jeffrey Hahn, Asst. Extension Entomologist

Tom Voigt.

Photo 1: Young eastern tent caterpillars constructing their tent after just emerging.

Be on the watch for eastern tent caterpillars.  There was a report of these insects at the end of last week in southeast Minnesota and it was reported in the Twin Cities at the beginning of this week.  The caterpillars are bluish black with yellow and a white stripe running the length of the top of its body. They are also mostly smooth except for a series of hairs sticking out along the sides of their bodies. They are two inches long when fully grown. 

However, the first sign you'll notice are the silken tents they create in the forks of branches.  After the caterpillars first hatch, they'll construct this webbing which serves as a shelter they use at night and during rainy weather.  The tent will be small at first but will increase in size and can eventually become quite conspicuous.  During the day they crawl out of these tents and feed on tree leaves.  Although they are found on a variety of hardwood trees, eastern tent caterpillars are particularly fond of fruit trees, including apple, chokecherry, crabapple, plum, and cherry.

Healthy, well-established trees can tolerate eastern tent caterpillar feeding.   Their feeding, as well as the presence of their webs, is just a cosmetic problem and only affects the trees' appearance.  However, young trees, as well as unhealthy, stressed trees, are more susceptible to feeding damage and should be protected.  

Also consider the size of the caterpillars.  As long as they are no more than half their full grown size, i.e. one inch or less, it is worth considering whether to treat them.  This is not an issue now as they are just emerging and they are all small.  However, if an infestation is discovered later, it is important to check to make sure they are not too large (larger than an inch).  The larger they are, the closer they are to being done feeding and then it is not worthwhile to treat them.

Terry Straub

Photo 2: Older eastern tent caterpillars on webbing.

A great non-chemical method to deal with eastern tent caterpillars is to wait until they have retreated back to their webbing at the end of the day or on a rainy day and then pull out the webbing, along with the caterpillars.  Then bury or bag them to properly dispose of them (you could burn them if it is permitted where you live).

There are a variety of residual insecticides that you can use if it is desirable to protect your trees.  Consider using products that have a low impact on the environment, such as Bacillus thuringiensis, spinosad, and insecticidal soap.  Bacillus thuringiensis is a particularly good product if the tree is flowering since it will not harm visiting honey bees.  If you use insecticidal soap, the product needs to directly contact the insects.  There is no residual activity so you may need to repeat the treatment.

It's Tick Season Now!

Jeffrey Hahn, Asst. Extension Entomologist

Jeff Hahn

Photo 1: American dog tick that was picked after a hike in the woods.

We have endured a long cold spring but now the weather is finally getting warmer so it is enjoyable to be outside again.  Finally, we are ready to enjoy our favorite outdoor activities.  You definitely want to get outside but with the return of nice weather also come ticks.  Take the proper precautions and protect yourself from these pests.

The two most common ticks in Minnesota are American dog ticks (also called wood ticks) and blacklegged ticks (formerly called deer ticks).  While American dog ticks are not important vectors of disease in Minnesota, they are nuisances because they bite us (also dogs too!).  Blacklegged ticks are also nuisances but they can be potentially more serious as they transmit diseases, including Lyme disease, anaplasmosis, babesosis, and Powassan encephalitis to people in Minnesota.  Of these, Lyme disease is the most common.

You are most likely going to encounter ticks in tall, grassy areas and in the undergrowth of hardwood forests so avoid those areas when possible.  When you are out in areas where ticks are known to occur, one of the best methods of protecting yourself is the use of a repellent.  You can apply DEET to both skin and clothes, while products containing permethrin should only be applied to clothes.  It is also very important to check yourself for ticks after coming back inside.  The sooner, you can find any ticks that may have crawled onto you, the sooner you can remove them, hopefully before they have started to bite you.  Ticks can't transmit disease if they are not biting.

For more information, see Ticks and their Control and Tick-borne diseases in Minnesota.

New Report on Bee Health from USDA and EPA

Jeffrey Hahn, Asst. Extension Entomologist

The following is from a news release that was issued on May 2, 2013

The United States Department of Agriculture (USDA) and the U.S. Environmental Protection Agency (EPA) released a comprehensive report last week on honey bee health. The report states that there are multiple factors playing a role in honey bee colony declines, including parasites and disease, genetics, poor nutrition and pesticide exposure.

In October 2012, a National Stakeholders Conference on Honey Bee Health, led by federal researchers and managers, along with Pennsylvania State University, was convened to synthesize the current state of knowledge regarding the primary factors that scientists believe have the greatest impact on managed bee health.

Key findings include:

Parasites and Disease Present Risks to Honey Bees:
• The parasitic Varroa mite is recognized as the major factor underlying colony loss in the U.S. and other countries. There is widespread resistance to the chemicals beekeepers use to control mites within the hive. New virus species have been found in the U.S. and several of these have been associated with Colony Collapse Disorder (CCD).

Increased Genetic Diversity is Needed:
• U.S. honeybee colonies need increased genetic diversity. Genetic variation improves bees thermoregulation (the ability to keep body temperature steady even if the surrounding environment is different), disease resistance and worker productivity.
• Honey bee breeding should emphasize traits such as hygienic behavior that confer improved resistance to Varroa mites and diseases (such as American foulbrood). 

Poor Nutrition Among Honey Bee Colonies:
• Nutrition has a major impact on individual bee and colony longevity. A nutrition-poor diet can make bees more susceptible to harm from disease and parasites. Bees need better forage and a variety of plants to support colony health.
• Federal and state partners should consider actions affecting land management to maximize available nutritional forage to promote and enhance good bee health and to protect bees by keeping them away from pesticide-treated fields.

There is a Need for Improved Collaboration and Information Sharing:
• Best Management Practices associated with bees and pesticide use, exist, but are not widely or systematically followed by members of the crop-producing industry. There is a need for informed and coordinated communication between growers and beekeepers and effective collaboration between stakeholders on practices to protect bees from pesticides.
• Beekeepers emphasized the need for accurate and timely bee kill incident reporting, monitoring, and enforcement.

Additional Research is Needed to Determine Risks Presented by Pesticides:
• The most pressing pesticide research questions relate to determining actual pesticide exposures and effects of pesticides to bees in the field and the potential for impacts on bee health and productivity of whole honey bee colonies.

Those involved in developing the report include USDA's Office of Pest Management Policy (OPMP), National Institute of Food and Agriculture (NIFA), Agricultural Research Services (ARS), Animal and Plant Health Inspection Service (APHIS), Natural Resource Conservation Service (NRCS) as well as the EPA and Pennsylvania State University. The report will provide important input to the Colony Collapse Disorder Steering Committee, led by the USDA, EPA and the National Agricultural Statistics Service (NASS).

An estimated one-third of all food and beverages are made possible by pollination, mainly by honey bees. In the United States, pollination contributes to crop production worth $20-30 billion in agricultural production annually. A decline in managed bee colonies puts great pressure on the sectors of agriculture reliant on commercial pollination services. This is evident from reports of shortages of bees available for the pollination of many crops.

The Colony Collapse Steering Committee was formed in response to a sudden and widespread disappearance of adult honey bees from beehives, which first occurred in 2006. The Committee will consider the report's recommendations and update the CCD Action Plan which will outline major priorities to be addressed in the next 5-10 years and serve as a reference document for policy makers, legislators and the public and will help coordinate the federal strategy in response to honey bee losses.

To view the report, which represents the consensus of the scientific community studying honey bees, please visit:

Psyllids Common in Homes this Spring

Jeffrey Hahn, Asst. Extension Entomologist

Small, fly-like insects have been appearing in people's homes this spring, especially around windows.  Although they look like gnats or flies (one person thought they looked like fleas), these insects are hackberry psyllids.  Despite their similarity to flies, these insects are more closely related to aphids and leafhoppers (they actually look like tiny cicadas).

Jeff Hahn

Photo 1: Close up of a hackberry psyllid.

Psyllids are about 1/8 inch long with a somewhat compact body.  Their wings, a mottled brown with small black and white spots, fold up tent-like over their backs.  During the spring and summer, they are associated with hackberry trees where they are gall producers on leaves.  Adults emerge from their galls in the fall.  Soon after that, they seek shelter to protect themselves from the winter; many end up in homes and other buildings, similar to boxelder bugs and lady beetles.

After they move into various cracks and spaces around the exterior of homes, psyllids remain dormant during the winter.  As warm weather arrives in the spring, many of them become trapped inside homes as they become active (they can also emerge inside buildings during mild winter days).  Fortunately, they do not live long indoors.  They also do not reproduce inside buildings; the individuals you see in the spring have been inside your home since fall.  They are harmless and just a nuisance. 

When you see psyllids in the spring, the only necessary control is physical removal.  Eventually they will either die inside or find a way to get outside.  In either case, this problem will be over this soon.  For more information about psyllids, including steps you can take in the fall to help prevent their entry into your home, see our publication on hackberry psyllids.  

Maria Taft

Photo 2: Hackberry psyllids around a window.

Wasp Queens in Homes during Early Spring

Jeffrey Hahn, Asst. Extension Entomologist

Some residents have recently been experiencing problems with wasps in their homes. The first reaction they generally have is that they have an active nest somewhere in their building. However, what people are actually seeing are just queens that have been hibernating since last fall.

Photo 1: Paper wasp queens (there is not a nest present when you see them in the spring.)

The old queen and all the workers die when freezing temperatures arrive in the fall; nothing is left alive in the nests. The only survivors are new queens that are produced at the end of summer. They leave their colonies and look for places to spend the winter. That could be under loose bark, under leaves, in or under logs, or in the cracks and crevices of buildings. Wasp queens usually overwinter individually. However, paper wasp queens tend to overwinter gregariously.

People can rest assured that if they see wasps in their buildings now, even if there are a lot of them, they are not nesting in their homes. The wasps are just overwintering insects that become active with warmer spring weather, like a boxelder bug or a lady beetle.

All the queens will eventually become active and either find their way outside or become trapped indoors. When you find wasps in your home at this time of the year, the best control is to physically remove them as you see them. They are generally sluggish when they first become active so you should be able to dispose of them with less risk of being stung.

To minimize this problem next year, it is important to seal up as many potential entry points around the outside of your home as possible. This can be supplemented with an insecticide treatment around the exterior during late summer or early fall. If this is difficult task for a homeowner, they can hire a pest management professional (pest control operator) to do this job.

New Sightings of Invasive Insect Pests

Jeffrey Hahn, Asst. Extension Entomologist

Two invasive insect pests, emerald Ash Borer (EAB) and brown marmorated stink bug (BMSB) were found in new locations during March.

Jeff Hahn

Photo 1: Emerald ash borer

EAB was discovered in Roseville (Ramsey County) on March 19 at the intersection of Snelling Ave. and Highway 36 by an arborist. The Minnesota Dept. of Agriculture (MDA) was contacted and after inspecting the tree was able to confirm one ash was infested by EAB. They also found three nearby trees that exhibited EAB symptoms and is suspected to be infested. MDA and the city of Roseville will conduct additional surveys in the area to verify the extent of the infestation. So far, the infestation only appears to be a few years old and likely represents a new pocket of infestation.

Despite this new infestation, EAB has still been confirmed in only four counties in Minnesota. In addition to Ramsey County, EAB has also been identified in Hennepin, Winona, and Houston Counties. You can use this MDA map to see where EAB has been confirmed in Minnesota.  For more information on EAB, see the Extension emerald ash borer page.

Jeff Hahn

Photo 2: Brown marmorated stink bug

In early March, BMSB was confirmed in Duluth (St. Louis County). A student working in the University of Minnesota Duluth insect collection found a stink bug that looked suspiciously like a BMSB. The specimen was brought to the attention of the collection's curator. She e-mailed pictures of the specimen to entomologists at the MDA and the University of Minnesota. The entomologists at both institutions confirmed the specimen was indeed BMSB. The insect had been originally collected in January, 2011, inside a home in Duluth.

So far, BMSB is not very common in Minnesota and all of the specimens of this insect have been discovered in homes during winter. The Duluth find is the furthest north this insect has been found in Minnesota. BMSB has been found primarily in the Twin Cities area (Anoka, Carver, Chisago, Dakota, Hennepin, Ramsey, Washington Counties) as well as in the southeast corner of the state (Winona County). For more information on BMSB, see the MDA fact sheet.

If you believe you have discovered an insect that is a brown marmorated stink bug or a spotted wing drosophila report it to the Minnesota Dept. of Agriculture at 888- 545-6684 or

Karl Foord - Extension Educator, Horticulture

At a recent conference on high tunnel horticulture we received an update on biological control from Carol Glenister, the president of IPM Laboratories. IPM Laboratories supplies and supports the successful use of healthy beneficial organisms for the biological control of pests.

nhm ac uk

Photo 1: Parasitoid Wasp Encarsia formosa

ipm UC Davis

Photo 2: Parasitoid Wasp Encarsia formosa

Encarsia Biological Services AU

Photo 3: Life cycle of parasitoid wasp Encarsia formosa

Forestry Images

Photo 4: View of a leaf surface with evidence of parasitoid wasp Encarsia formosa activity

Photo 5: Parasitoid wasp Eretmocerus spp.

Photo 6: Small lady bird beetle Delphastus spp.

Carol has coined the term "guardian plants" that function in the following ways: 1) are more attractive to the pest species than the crop being grown i.e. 'indicator' or 'trap' plants, 2) provide forage for natural enemies of the pests i.e. 'habitat' plants, and 3) provide forage for non-pest prey species that serve as an additional food source for natural enemies or serves as a reproductive site for natural enemies i.e. 'banker' plants.

Biocontrol Cornell

Table 1: Parasitoids

The indicator plants let you know the pest is present and the habitat and banker plants provide resources that encourage the natural enemies to remain and thrive on site.

Biocontrol Cornell

Table 2: Predators

Biocontrol Cornell

Table 3: Pathogens

In natural populations the predator numbers shadow the prey numbers, but the prey species always reproduce more rapidly so there is often a delay in control. If the control comes after the prey has damaged our plants then the predator hasn't benefited our production system. If the two-spotted spider mites are finally controlled by the predatory mites but your tomatoes performed poorly during the battle, there is little cause for celebration. The key is to have predator numbers in sufficient quantity early in development to keep prey damage below an acceptable threshold.

This means knowing what pest you expect to encounter, placing the proper indicator plants, monitoring for pest activity, getting predator species in a timely fashion, providing habitat plants and tracking pest and prey activity and numbers.

Natural enemies such as the following are presently being used to control whiteflies in greenhouses; two parasitoid wasps (Encarsia formosa Photos 1 - 4, and Eretmocerus eremicus Photo 5), and a small lady bird beetle (Delphastus catalinae) Photo 6. Note the incredibly small size of these insects - less than 1 mm in length.

In one experiment Lantana was used as a guardian plant among herbs such as oregano and lemon verbena, and the Encarsia formosa wasp was used as the prey species. The ratio of whitefly pests found on Lantana to those on the herbs was 79 to 1. The whitefly pest was drawn to the trap plant where it met its demise at the "hands" of the Encarsia wasp. This experiment can be viewed in greater detail at

There is a great deal of research being conducted in this area, especially on the functioning of these bio-control organisms in outdoor environs. Consider the number of organisms functioning as parasitoids, predators, and pathogens as noted in Tables 1 - 3.

This is a fascinating research arena and one worth tracking advancements.

Pavement Ants in Homes During Winter

Jeffrey Hahn, Asst. Extension Entomologist

Winter is not a time when you typically expect to encounter ants in your home. However, it happens more often than you might think. One of the more common ants found in homes and other buildings is pavement ants. This ant is 1/8th inch long and is reddish brown, although it can range in color from light brown to dark brown to almost black. With magnification you can see that this ant has a two-segmented petiole (the waist between the thorax and the abdomen) and two short spines projecting from the thorax.

Jeff Hahn

Photo 1: Pavement ant worker. Note the two-segmented petiole and two small spines on the abdomen.

Pavement ants like to nest in the soil under or besides objects, such as stones, bricks, sidewalks, and driveways. They can also nest under the concrete slabs of homes as well as in wall voids. They typically nest near a heating source which allows the ants to be active during winter. They can follow pipes that go through slab to move up into the living quarters of homes thorough expansion joints, under baseboards and floor registers. Sometimes large numbers of winged pavement ants are found which are the reproductives of the colony, i.e. females and males.

Pavement ants can infest foods; they like protein and grease, such as meats, cheese, dead insects, dry pet food, and peanut butter, as well as a variety of sweets. Other than that, pavement ants are mostly annoying and are not particularly damaging to homes.

If you are finding pavement ants in your home, try to determine from where they entering. If you can determine they are moving through a crack, e.g. in an expansion joint, try to seal it to help keep pavement ants out. If you are not able to find how they are getting into your home, then try baiting them.

Jeff Hahn

Photo 2: Pavement ant swarmers can be sometimes seen indoors. They are just a nuisance.

Select a bait that is effective for grease feeding ants and place it where you are commonly finding them. Don't be surprised if there is an increase in the number of workers that are around the bait. That's good, the more ants that take bait back to the nest, the more likely you can eliminate it. Don't spray the foraging workers. It doesn't have any impact on the colony and will also lessen the ability of the workers to take bait back to the nest.

If you are not successful in your efforts to get rid of pavement ants or you would rather have someone control them for you from the start, talk to a professional pest management service about treating your ants.

Not all ants found indoors during winter will be pavement ants. People can also potentially see carpenter ants, Pharaoh ants, yellow ants, and thief ants in their homes during the winter. Their habits differ as do the methods for treating them. If you have any doubt as to what kind of ant problem you have, get them identified them by an expert.

Minnesota Fruit and Vegetable First Detector Program

Jeffrey Hahn

Photo 1: Attendees examining pest damage at a previous First Detector workshop. A new First Detector workshop is being offered to discuss invasive pests of fruits and vegetables.

The Minnesota Fruit and Vegetable First Detector Program is a new joint program between the University of Minnesota Extension and the Minnesota Department of Agriculture to increase awareness and detection of invasive diseases and insect pests of fruits and vegetables. There are two ways that you can be involved.
  1. Attend a workshop about invasive pests that threaten Minnesota fruit and vegetables. Learn how to identify invasive pests and distinguish them from common look a likes. Find out the proper steps to take if you suspect you have found and invasive pest.
  2. Become a first detector volunteer. Act as a local resource to help state officials respond to calls made to the Arrest a Pest Hotline. First Detectors are volunteers trained to help citizens diagnose and report possible infestations of invasive species to the Minnesota Department of Agriculture. First Detectors are a part of the National Plant Diagnostic Network (NPDN) First Detector Program which promotes the early detection of invasive plant pathogens, arthropods, nematodes and weeds.

Still Time for Sanitation

Michelle Grabowski and Jeff Hahn, UMN Extension

M. Grbaowski, UMN Extension

Photo 1: Dead daylily leaves with visible dark spots from daylily leaf streak

The ground is cold, trees have dropped their leaves, and perennial and annual flowering plants have died back to the ground. Yet there is still time for a garden clean up that will reduce the number of pathogens and insect pests that survive from this season to the next. Sanitation, the removal of a infected plant material, is one of the basic steps of integrated pest management. It is a chemical free way to reduce pest damage in future growing seasons.

For sanitation to work you must remove the part of the plant that is infected with a pathogen or insect pest completely from the area and destroy it. Disease infected plant material can be burned, buried or composted. Check with local laws about burning plant material. Composting will kill pathogens and insects only if the pile gets hot. If your backyard compost pile is a slow pile of cold rot, consider taking infected material to a municipal compost site. These sites have so much plant residue to work with they manage the pile to heat up so the material breaks down quickly. It is important to realize that it might take a few years of good sanitation to truly get ahead of a fungal or bacterial plant disease. Fungi are known to survive 2-4 years in buried plant debris, bacteria typically can survive 1-2 years.

Here is a list of a few plant problems that would benefit from fall sanitation efforts.

M.Grabowski, UMN Extension

Photo 2: Fallen leaves at the base of this rose shrub should be cleaned up and removed from the garden to prevent overwintering of black spot

Trees and Shrubs
Apple Scab on crabapple or apple trees
Black Spot on rose
Any leaf spot disease like tar spot on maple, anthracnose or linden leaf blotch
Rake up and remove those leaves or they will produce fungal spores to start next years epidemic!

In the Flower Garden
Fungal and bacterial leaf spot diseases on perennials like Botryis leaf spot on Peony, Daylily leaf streak, Iris leaf spot. Sorry but sanitation will not help reduce powdery mildew.
Remove plants at ground level. Clean up all stems and fallen leaves. The pathogens survive in any infected plant material.

Four Lined Plant Bug
Iris Borer
These insects lay eggs on plant material late in the growing season. In spring the new insects cause damage on these plants.

In the Vegetable Garden
Septoria Leaf Spot on tomato
Early Blight on Tomato
Bacterial leaf spot on pepper
Remove plants at ground level. Clean up all stems, fallen leaves, and rotten fruit. Infected plant material can be removed from the garden or tilled under.

Squash Bug
Asparagus Beetles
These insects spend the winter as adults under plant debris. By removing plant debris in general the number of overwintering sites for these insects is reduced.

Bug Bombs and Bed Bugs

Jeffrey Hahn, Asst. Extension Entomologist

The resurgence of bed bugs in the U.S. over the last 10 or so years has increased many people's awareness of these biting insects. They have presented residents and pest management professionals a tremendous challenge to detect and eliminate them. A popular tactic used by residents in bed bug control is the application of total release foggers, also known as bug bombs. Many people have turned to these products to help them control their bed bug problems. But are they effective? This question was examined in a research study conducted by Drs. Susan Jones and Joshua Bryant at Ohio State University.

Jeff Hahn

Photo 1: Bug bombs are not effective in controlling bed bugs. One reason is the insecticide does not reach where the bed bugs hide.

They compared three popular bug bombs that are available to residents. The Hot Shot Bedbug and Flea Fogger is specifically labeled for control of bed bugs and was more extensively tested. They also examined the Spectracide Bug Stop Indoor Fogger and Eliminator Indoor Fogger. Although these products are not listed specifically for bed bugs, they are labeled for flying and crawling insects and could be used by Minnesotans in an attempt to eliminate bed bugs.

Jones and Bryant tested these products against five different populations of bed bugs collected from home infestations in Ohio. They also tested these bug bombs against a strain of bed bugs that has been reared exclusively in a laboratory for 39 years. These bed bugs have never been exposed to pesticides and are susceptible to bed bug products. All of these bed bugs were exposed to the Hot Shot Fogger in three scenarios, direct exposure, optional harborage (they could hide under filter paper), and forced harborage (they were covered by a thin fabric covering). The other two foggers were used only in direct exposure and optional harborage experiments (they were unable to complete the Eliminator Fogger and optional harborage trial) against two of the field collected bed bugs as well as the continuously lab reared bed bugs.

All three bug bombs had generally little effect on the 'wild' collected bed bugs in the direct exposure experiment (with one moderate exception). However, most or all of the lab reared bed bugs were killed. Similar results were seen in the optional harborage experiment except that it took longer to kill most or all of the lab reared bed bugs. In the forced harborage trial, all bed bugs, including the susceptible lab reared bed bugs, were minimally affected by the Hot Shot Fogger.

So what does all of this mean? The short answer is that bug bombs are not effective in controlling bed bugs. There are several reasons why this is true. First, the bed bugs that we battle in our homes are generally not affected by the insecticides contained in bug bombs, even if they are directly exposed to them. There has been growing evidence of varying degrees of bed bug resistance (i.e. they are much less vulnerable) to pyrethroid insecticides which is the primary active ingredient of bug bombs. Only bed bugs that have never been exposed to insecticides could be easily killed and then only if they were directly exposed or were exposed before they sought a place to hide. This research project also concluded that bug bombs were ineffective because of short exposure times, the low concentration of insecticides, and the lack of residual activity.

Bug bombs are also not effective because the insecticide does not penetrate to the harborages where bed bugs hide. This is critically important as these biting insects spend most of their time hiding in cracks, tight spaces, behind and under objects, and similar places (up to 80% of them hide in harborages during the day). They are infrequently out in the open for any length of time and even then just a few at a time. For bug bombs to be effective, they need their target insect to be out in the open long enough for the insecticide to reach them. This research also found that even the susceptible populations of bed bugs were largely unaffected when they were in protected sites.

While bug bombs are not the answer, there are a lot of positive steps you can take to help control a bed bug infestation. See the University of Minnesota's Let's Beat the Bed Bug web page. From there you can access a variety of fact sheets and other sources of information as well how to contact the Bed Bug hotline.

The results of this research were published in the Journal of Economic Entomology, 105(3): 957-963 (2012).  A summary of this research was also published in Pest Control Technology in the October 2012 issue.

An Unusual Insect Found in Minnesota: Drywood Termites

Jeffrey Hahn, Asst. Extension Entomologist

Termites are present in Minnesota but they are not common. They are found in southern Minnesota up to about the Twin Cities area and very rarely discovered, if ever, in central and northern Minnesota. Minnesota's native termites are subterranean termites, Reticulitermes spp. They maintain colonies in the ground and attack wood that is contact with the soil. You rarely see the termites themselves because the bulk of them stay inside the colony while those that travel outside of it move about in mud tubes they construct so they can maintain the proper temperature and humidity they need to survive.

That is why the discovery of winged termites in a home in Minneapolis during September was so interesting and unusual. First, when termites swarm, i.e. winged forms leave the nest en masse, they do so in the spring (and this is very rarely seen in Minnesota). Even more interesting was when the termites were examined more closely, they were identified not as the local subterranean termites but as drywood termites. This group of termites is not native to Minnesota but is most commonly found along the costal areas of the southern U.S. from North Carolina to California.

Jeff Hahn

Photo 1: Drywood termite queen

At first, just a single winged termite was found at a window at this home. Shortly after that, about 100 were found behind a couch. In the next couple of weeks, dozens more were found either behind or under the couch. The resident had owned this piece of furniture for 14 years. She had purchased it in Minnesota and never lived outside of the upper Midwest with it. The resident had never received any items mailed from areas where drywood termites are native nor had she ever noticed termites or sawdust in her home before, especially around the couch.

This brought up several excellent questions: where did the termites come from; how long have they been in the couch; and have they spread into other areas of the house? Information about drywood termite biology helped to answer these questions.

Although the couch had never traveled to any drywood termite endemic areas after the homeowner bought it, it undoubtedly was built and/or stored in a warehouse somewhere in the south where these termites are native. It was there that the couch became infested. You wouldn't normally think that insects could infest a piece of furniture for 14 years without their presence being noticed but drywood termite colonies grow very slowly and it isn't unusual for them to take that long before they are mature enough to produce new queens. So it is extremely likely that the termites were in the couch when it was bought and had been in the furniture during that entire time the resident owned it. Because the termites were confined to the couch, they did not spread to other areas in the house.

Fortunately for the homeowner, the only necessary control was to remove the couch from her home. It was taken away by a local pest management company, heat treated to kill the termites, and then properly disposed of. All's well that ends well.

Boxelder Bugs Are on the Move

Jeffrey Hahn, Asst. Extension Entomologist

It has been a long summer but fall is finally catching up with us. Fall is also the time when nuisance insects fly to buildings and other structures to look for places to spend the winter. One insect to be on the watch for is the boxelder bug Although these orange and black insects are around every year, they have been particularly numerous this summer. The weather has a lot to do with that as years of hot, dry summers are very favorable for their development and we often experience much larger populations of them then.

Jeff Hahn

Photo 1: A nemesis, the boxelder bug, is present in large numbers this year.

Right now a lot of people are finding large numbers of boxelder bugs on the sides of their homes. Being on the outside of structures is not necessarily bad if boxelder bugs would just stay there but eventually many of these insects will get inside these buildings. There are not any practical home remedies for dissuading boxelder bugs from landing on homes, although people have tried solutions such as throwing boiling water on them and trying to kill them with fly swatters. While people may not like all of the boxelder bugs on the outside, people should aim at preventing these insects from getting into their homes.

Control is two fold. First, seal as many spaces and openings as possible that may allow boxelder bugs into your home. Concentrate around widows and doors, roof lines, where utility lines enter buildings, and where horizontal and vertical surfaces meet. Second, supplement this with a residual insecticide application, especially around areas where boxelder bugs are most likely to gain access. This is something homeowners can try themselves; common active ingredients that could be used would include permethrin and beta-cyfluthrin (make sure products are labeled for the outside of homes). Or they can contact an experienced pest management service to make this application for them.

Not only is it important to take action now to keep boxelder bugs out of your home this fall but a lot of these insects can also become nuisances later during days of mild winter temperatures. Once they get inside, they seek out wall voids, attics and other nooks and crannies in which to hibernate. It is important for boxelder bugs to find a place that is unheated and will remain cold during winter. As long as they are in such place, they will remain dormant.

Jeff Hahn

Photo 2: Boxelder bugs looking for overwintering sites on a home.

However, as temperatures warm up the sites where boxelder bugs are hiding, they will wake up, 'thinking' spring has arrived. They will move towards the warmth and will end up being trapped indoors. Boxelder bugs typically aggregate in clusters; insects on the outer part of these clusters will become active first. This results in boxelder bugs emerging at different times. When boxelder bugs appear in the middle of the winter, it appears that they have been reproducing indoors, however what people are seeing are adults that entered their homes the previous fall. (Note: Boxelder bugs are occasionally observed laying eggs indoors. However, either immature boxelder bugs don't hatch from them or if they do the young bugs do not have food and do not live long. They certainly are not able to mature into adult bugs.)

The boxelder bugs that get inside your home can definitely be annoying; in fact the more there are the more bothersome they usually are. Fortunately, boxelder bugs are harmless to people. They may occasionally stain surfaces but are otherwise not damaging to property. Once they are in your home, you have few options to deal with them. The easiest solution is physical removal, such as with a vacuum cleaner. This may not always be helpful when boxelder bugs are really numerous, but that is still the best control. This is why the more you can prevent from entering your home during fall, the fewer you will deal with later.

Spotted Wing Drosophila Update

Jeffrey Hahn, Asst. Extension Entomologist

Jeff Hahn

Photo 1: Spotted wing drosophila female on blackberry

Since the presence of spotted wing drosophila (SWD) Drosophila suzukii was first confirmed in Minneapolis at the beginning of August (see August 15, 2012 Yard and Garden News, ), there have many reports of this fruit fly in other parts of the state. As of the end of August, SWD has been confirmed in 11 counties and suspected in another three, ranging as far north and west as Alexandria (Douglas County) and down to the southeast corner of the state.

Although SWD was found for the first time this year, it is possible that it had been present in Minnesota a year or two earlier but at levels to low to be detected. Regardless of when it first appeared in Minnesota, it is likely that the abundance we experienced this year was the result of spring weather that literally carried up large numbers of SWD on storm fronts. We have seen a variety of other insects this year that were likely influenced by weather patterns blowing them up to Minnesota including insects that we would not normally see in such large numbers (e.g. variegated cutworm) and insects that normally don't occur in Minnesota all (e.g. genista broom moth)

Jeff Hahn

Photo 2: Spotted wing drosophila damaged blackberries

SWD attacks many types of ripening, thin-skinned, soft fruit, especially cane fruit, like raspberries and blackberries, blueberries, strawberries, grapes, cherries, and plums. There has been some question about whether they will attack tomatoes but it is doubful tomatoes are attractive to them. If you have a garden with any of these fruits, there are not a lot of options for protecting them this late into the season. The primary control is treating the adults when they are first present to prevent them from laying eggs in the fruit. Once fruit is infested, you can not effectively treat the larvae as they are protected inside the produce. Infected fruit becomes soft and decays and sometimes becomes discolored. When you probe into the fruit, you can usually see the small white maggots that are responsible.

There are some cultural control steps you can take to help minimize SWD. First, pick the berries frequently when they are ripening. Remove and destroy any overripe or obviously infested fruit. Don't place infested produce into compost piles as they will likely be able to complete their life cycle and emerge as adults. It is better to place them in plastic bags tightly tied shut and thrown out. You could also place infested fruit in clear plastic bags and leave them in the sun; the heat should kill them if left out for 12 - 24 hours. You could also freeze them, making sure that the fruit is frozen for a long enough period to kill the maggots.  Burying is not a good option as adults can still emerge even when buried down to 12 inches.

Even fruit that looks fine could be infested. Use your discretion as to whether you save or dispose of this produce. Should you inadvertently eat infested fruit, ingesting the maggots is not harmful to people. Using apparently uninfested fruit for cooking should not be a problem; any flies that are present would not survive the process.

Bob Koch - MN Dept. of Ag.

Photo 3: Spotted wing drosophila larvae (maggots) in damaged fruit

SWD overwinters as an adult. It is unclear whether they can survive a Minnesota winter. This fly was not detected in Wisconsin in 2011 after it had been first found there in 2010. That could bode well for us but time will tell what kind of a problem we will face with SWD. It will be important to set up traps and survey for them in 2013.

If you encounter flies or maggots in fruit that you suspect are SWD, contact the Minnesota Department of Agriculture's "Arrest the Pest" hotline at 1-888-545-6684 or Please note the location and date of collection for the specimen.

For more information on SWD, see also the University of Minnesota's VegEdge web page.

Minnesota's Newest Fruit Pest, the Spotted Wing Drosophila

Bob Koch, Minnesota Department of Agriculture
Jeff Hahn and Eric Burkness, University of Minnesota

A new fruit pest, the spotted wing drosophila (SWD) (Drosophila suzukii), has arrived in Minnesota. This pest feeds on small fruits and stone fruits. The SWD is an invasive pest of Asian origin that was first detected in the continental United States in California in 2008 and has since spread to several western and eastern states. It was found in Minnesota in August, 2012.

The first two detections of this pest were made by members of the public who reported the flies to the Minnesota Department of Agriculture (MDA). First, a homeowner from Hennepin County contacted the MDA about some flies she found in a yeast-baited trap she placed near a raspberry patch. Days later, the MDA was contacted by a citizen who found an abundance of maggots in some wild raspberries picked in Ramsey County. The MDA quickly followed up on both of these reports to visit the sites, collect specimens and confirm the identity of this new pest. It is impressive that people noticed such a small fly (or maggot), realized that it could be a new invader, and knew to contact agricultural authorities regarding the finds. It goes to show how much people care about protecting our resources.

Bob Koch, Minn. Dept. of Ag.

Photo 1: Close up of a male spotted winged drosophila. Note the spot on the wing

The SWD looks very similar to the small fruit flies you might occasionally see flying around overripe fruit on your kitchen counter. However, unlike these other flies, which typically feed on overripe or deteriorating fruits, the SWD feeds on healthy, intact, ripening fruits. In particular, the SWD will feed on thin-skinned, soft fruits such as raspberries, blackberries, blueberries, strawberries, grapes, plums and cherries.
The SWD is difficult to distinguish from other species of small flies. The SWD is a small fly, only 2 - 3 mm (1/12 - 1/8 inch) long, with yellowish-brown coloration and prominent red eyes. Male SWD have dark spots near the tips of the clear wings. Several other species of small flies with spots on their wings can easily be confused for SWD. Female SWD have few distinguishing characters and are even more difficult to identify. Larvae of SWD are white with a cylindrical body that tapers on both ends. To date, SWD is known to be an outdoor pest; fruit flies found indoors are likely to be a different species.

Female SWD use a saw-like egg laying structure to lay their eggs in ripening fruits. The larvae of the SWD then feed within the fruits causing brown, sunken areas. Sometimes the symptoms will not show until after the crops are harvested and sometimes not until the fruits are in possession of the consumers. In addition to the damage caused directly by the larvae, the feeding makes the fruits susceptible to infestation by other insects and rot fungi and bacteria. The larvae will then leave the fruits to pupate and later emerge as adults. Multiple generations of SWD can occur in a year, with populations building throughout the summer. The overwintering stage of the SWD is the adult; however, its ability to survive Minnesota winters remains unknown.

Hannah Burrack, North Carolina State University,

Photo 2: SWD damage to raspberry. Note the two larvae that just visible.

With this pest being so new to Minnesota and the United States, little is known about how big of an impact it will have and what management tactics will be most effective. The MDA will be working with the University of Minnesota (Extension and the Department of Entomology) to determine how widespread this pest is in Minnesota and to alert farmers and gardeners of its presence and potential impacts. The University of Minnesota will also be developing recommendations for management of this pest on Minnesota fruit crops. SWD could be particularly devastating to blueberry, raspberry and grape growers, but we will need more information on when the pest is active in Minnesota and how well it can survive our winter weather.

Extension programs from other states have suggested several items for consideration in management of this pest. Sanitation is an important consideration to lessen local buildup of SWD populations. Sanitation practices include frequent harvest of crop to ensure ripe fruits are not in field for extended period of time and removal and destruction of old fruit remaining on stems and fallen fruit. Furthermore, crops can be monitored with traps baited with yeast or vinegar; however, yeast-baited traps appear more effective. Traps should be checked frequently (at least weekly) to determine the presence and abundance of SWD males and females. Monitoring for activity of SWD adults is also important, because once eggs are laid in the fruits it will be too late for other management tactics (for example, insecticides) to be effective. If SWD are found in the traps, an insecticide that is registered for use in the specific crop and effective against the pest should be applied. University of Minnesota Extension is evaluating what insecticide options will be effective in Minnesota. After treatment, monitoring of SWD should continue, with additional timely treatments applied as needed.

The adult flies are difficult to distinguish from other small flies; however, if you find an abundance of small, white maggots in what were apparently healthy fruits at the time of harvest, contact the MDA's "Arrest the Pest" hotline at 1-888-545-6684 or at  For more information, and SWD updates, please see the University of Minnesota SWD Web page.

Genista Broom Moth

Jeffrey Hahn, Asst. Extension Entomologist

An interesting caterpillar has been found apparently for the first time in Minnesota in several areas of the state. A genista broom moth caterpillar, Uresiphita reversalis, is about one inch long when fully grown. It's a pretty insect with a black head with white markings and a slender yellowish green or mustard colored body. There is a series of black and white colored tubercles (raised spots) running down its body with white hairs coming out of them.

Jeff Hahn

Photo 1: Genista broom moth caterpillar on Baptisia.

When gardeners have discovered this insect in Minnesota, it has been feeding on false indigo, Baptisia. According to BugGuide this caterpillar has also been reported to feed on Acacia, Genista, Lupinus, Texas Mountain Laurel (Sophora secundiflora) and other pea family shrubs as well as Crapemyrtle (Lagerstroemia indica) and honeysuckle (Lonicera spp.).

The adult has a conspicuous snout and holds it wings in a delta shape when at rest. The forewings are light to medium brown with several small dark spots and marking while the hind wings are yellow or orange (see the Moth Photographers Group for images and the known distribution in the U.S.).

Genista broom moths are generally distributed throughout much of the southern U.S. It has been found as close to Minnesota as Iowa and Wisconsin (which are also seeing somewhat higher than normal numbers of this moth this summer). The appearance here of this insect is likely the result of migrant moths moving into Minnesota, possibly with the help of weather patterns. A perusal of the University of Minnesota's Insect Museum emphasizes that lack of genista broom moths found in Minnesota; only nine adult moths were found in the collection and none of them are from Minnesota.

We appear to be near the end of their feeding now as larvae look like they are getting ready to pupate. If you find these caterpillars in your garden and they are about one inch long, you can ignore them as they are essentially done with their feeding. If they are smaller, you have a few options. Probably the easiest thing you can do is to handpick them. It they are numerous, consider a low impact insecticide, such as insecticidal soap, spinosad, or Bacillus thuringiensis.

It is unclear whether genista broom moths will survive winters in Minnesota. If you have discovered this caterpillar in your garden, please contact the author ( and report it. We are trying to establish where these insects have been discovered and whether they are found in the same sites next summer.

Cicada Killers

Jeffrey Hahn, Asst. Extension Entomologist

Jeff Hahn

Photo 1: Cicada killer carrying a cicada back to her nest.

There have been many reports of cicada killers, Sphecius speciosus, nesting in yards, gardens, parks, and other areas. These wasps are large, 1 - 1 ½ inches long, with a black and reddish brown thorax, amber colored wings, reddish brown legs, and a black abdomen with yellow bands. They are found nesting in the soil where they prefer, well-drained, light soil exposed to full sun. A cicada killer is a solitary wasp, so you will only find one wasp per burrow. However, they are gregarious, meaning that you can find a number of them in a small area, sometimes establishing large aggregations of nests.

As their name suggests they catch cicadas. Cicadas are stout, winged insects common during the summer. However, people are more likely to hear them as they produce a power line like hum that is heard during the day. Once a cicada killer captures a cicada, she uses her stinger to paralyze it. She carries the cicada back to her nest where she will lay an egg on it. Once the grub-like larvae hatches, it feeds on the cicada. After it consumes the cicada, it pupates and remains in the burrow until next year.

Despite their size, cicada killers are not dangerous. While females have stingers, they are unaggressive and ignore people. They do not have an instinct to protect their nests (like yellowjackets and honey bees) and you can walk amongst them with little worry. Of course if you handle a cicada killer or it feels threaten, it can sting to protect itself.

Males on the other hand are territorial, looking to mate with females and chasing away other males. They can act aggressively if you enter an area they are patrolling. They will fly up to you, challenging you. Fortunately, it's all bluff as they lack a stinger and are harmless. Admittedly, that can be challenging to hold your ground when a large wasp is zooming around you but they can not hurt you.

Jeff Hahn

Photo 2: Pile of dirt in garden due tunneling by a cicada killer.

Fortunately, cicada killers are just annoying. It is possible that their tunneling can undermine patio bricks but they are not going to be more of a problem than that. If you have property where cicada killer are nesting, there are couple of options to consider. The first is to ignore them and let them run their course. Remember, there is very little risk of stings and they will go away on their by the end of the summer. However, if they enjoyed nesting there this year, there is a good chance they will return next year.

Another option is to treat the nests. Keep in mind that generally broadcast spraying the areas where they are nesting is not very effective. Instead, apply an insecticide into each individual nest entrance. Dusts are most effective, although sprays can help reduce numbers. Effective active ingredients include permethrin and carbaryl. If you have trouble finding an appropriate insecticide, contact a lawn service to treat the cicada killers for you; they have access to turf products, like those containing fipronil or deltamethrin, that home residents can not find.

Karl Foord - Extension Educator, Horticulture

I was vacationing at Scenic State Park last month, and while driving down the road to Big Fork I saw a patch of common milkweed (Asclepias syriaca) along the roadside (Photo 1). I decided to stop and see if milkweed's reputation as a butterfly magnet was truly deserved.

Karl Foord

Photo 1: Milkweed Patch

I stood in the patch for an hour. It was like being in a natural butterfly house. The amount of activity was amazing. I would estimate there to have been at least 100 butterflies in this approximately 15' x 20' patch. There was also a dizzing array of butterfly species. I have attempted to record this diversity with photographs, and using Larry Weber's Butterflies of the North Woods, have identified 26 different species.

I will divide the findings into three articles; brushfoots, skippers, and a collection of sulphurs, coppers, hairstreaks, and day-flying moths.

Karl Foord

Photo 2: Monarch Adult and Caterpillar

Karl Foord

Photo 3: Admiral and Ladies

Karl Foord

Photo 4: Great Spangled and Atlantis Fritillaries - upper wing

Karl Foord

Photo 5: Great Spangled and Atlantis Fritillaries - under wing side view

Karl Foord

Photo 6: Aphrodite Fritillary and Common Wood-Nymph

Karl Foord

Photo 7: Crescents

Karl Foord - Extension Educator, Horticulture

This is a continuation of the butterflies encountered in a roadside milkweed patch.

Karl Foord

Photo 1: Peck's and Delaware Skippers

Karl Foord

Photo 2: Silver-spotted and Least Skippers

Karl Foord

Photo 3: Long Dash and Dion Skippers

Karl Foord

Photo 4: Dun Skippers - Male and Female

Karl Foord

Photo 5: Unidentified Skipper

Karl Foord - Extension Educator, Horticulture

This is a continuation of the butterflies encountered in a roadside milkweed patch.

Karl Foord

Photo 1: Clouded and Orange Sulphurs

Karl Foord

Photo 2: Pink-edged Sulphur

Karl Foord

Photo 3: Bronze Copper and Acadian Hairstreak Butterflies

Karl Foord

Photo 4: Day-flying Moths

In conclusion, I would have to say that milkweed certainly lives up to its reputation as a butterfly magnet. I am looking for a place to establish a milkweed patch and invite the butterflies.

Deer Flies Common This Year

Jeffrey Hahn, Asst. Extension Entomologist

Deer flies (family Tabanidae) have been particularly bothersome in many areas of Minnesota this year. These flies are about 1/4 - 3/8 inch long and are stout-bodied. They have yellow or black colored bodies with dark colored markings on their wings.

Mark 'Sparky' Stensaas

Photo 1: Typical deer fly. Note the iridescent eyes.

The larvae live in aquatic or semiaquatic areas, like marshy areas, streams and ponds. Adults are found near these breeding grounds, especially along the edge of woodlands but they are strong fliers and can be found miles away from these breeding areas. Watch out for deer flies especially on sunny, calm days. They have a tendency to wait in shady areas for hosts and ambush them as they move past. Deer flies primarily use sight to find a host and seem to be particularly attracted to moving, dark shapes.

They go for the head and neck when biting people. They inflict a painful bite as they use knife-like mouthparts to slice a wound in the skin and feed on the resulting blood. Fortunately, deer flies do not vector disease in Minnesota, although some people can suffer allergic reactions to the bites. In addition to humans, these biting flies also attack many different animals, including deer, horses, and cattle. Deer flies are most common in June and July, although can persist throughout the summer.

Unfortunately, we have very limited options when it comes to preventing deer flies from biting us. It is not practical to control immature deer flies by eliminating breeding sites, i.e. marshes, streams, and ponds. There are just too many potential sites to treat and the risk of environmental harm is too great. It is also prohibitive and impractical to treat adult flies in yards, parks and others areas with insecticide applications.

Jeff Hahn

Photo 2: Deer fly taking a blood meal. Knife-like mouth parts usually results in a painful bite.

Control of deer flies usually boils down to personal protection, i.e. protective clothing, such as hats, long-sleeved shirts, and long pants to help protect exposed skin. You can also try a mosquito repellent, i.e. DEET and permethrin (follow all label directions), although the results are inconsistent.

There are also a variety of devices that purport to protect people from deer flies. One method involves placing sticky patches on the back of hats. In theory deer flies land and stick to the patch before they can bite you. Another device is the trolling deer fly trap. You use a blue cup covered with glue. You mount it either to hats or caps or machinery, such as lawn mowers.The idea is the deer flies are attracted to the cup, land and get stuck on the glue, preventing them from biting you. It is advertised to be most effective when it is moving.

Karl Foord - Extension Educator, Horticulture

In the article Swamp Milkweed - Great for Nectar - Bizarre Flowers that appeared in the June 15 Issue of Yard and Garden News, I lamented the fact that I had no pictures of insects carrying the pollinia of milkweed.

Although the pictures in this article are of insects on common milkweed (Asclepias syracia) and not Swamp Milkweed (Asclepias incarnata) the flowers are similar enough to be applicable.

Please note the pollinia on both a native bee and a fritillary butterfly.

Karl Foord

Photo 1: Milkweed Pollinia taking a ride on a native bee

Karl Foord

Photo 2: Pollinia taking a ride on a Great Spankled Fritillary (Speyeria cybele)

Vareigated Cutworm Damage

Jeffrey Hahn, Asst. Extension Entomologist

Jeff Hahn

Photo 1: Variegated cutworm damage on hosta

A large flight of variegated cutworm moths moved through Minnesota as well as Wisconsin this spring. This was particularly noticeable when clusters of eggs were found on many buildings and other structures during May (see June 1, 2012 Yard and Garden News)

The result of this activity is now being felt in home gardens as many different herbaceous plants that are being damaged by their feeding. Unlike subterranean cutworms that many gardeners are familiar with, variegated cutworms are a type of climbing cutworm that will feed on the foliage of plants. They typically chew irregular holes between the veins on the leaves. They have also been known to bore into flower buds. Be careful not to confuse variegated cutworm feeding with slug damage which can look similar. Slug feeding usually results in more ragged, irregular holes but to be sure, you may have to catch the culprits in the act.

Variegated caterpillars are generally dark-colored, ranging from brownish to black. There are four to five yellowish diamond-shaped spots on the top of the body starting at the head. They may also have a dark-colored 'W' on top of its body near the posterior. Like other cutworms, variegated cutworms curl into a ball when they are disturbed. These cutworms are large when mature, growing to 1½ to two inches long.

Jeff Hahn

Photo 1: Variegated cutworm

The biology of variegated cutworms in Minnesota is not clearly understood. They apparently can overwinter in Minnesota either as pupae or larvae. However, most of them are probably carried up on the jet stream as adult moths and deposited into Minnesota during spring. They are reported to have two generations in the northern U.S. so we can expect to see them throughout the summer.

If you are experiencing problems with variegated cutworms, you have several options for managing them. You can try handpicking them. You might even be able to put out boards and trap some. If the problem is severe enough, you may resort to insecticides. Spinosad is a good option if you are looking for a low impact product. There are also a variety of residual insecticides to choose from, including permethrin, bifenthrin, cyfluthirn, and carbaryl.

A question that gardeners in northern Minnesota are asking is whether they will now start seeing this insect every year when they rarely or never saw it before. The good news is that the odds are in northern Minnesota's favor for not witnessing a repeat performance by variegated cutworms next year. We would have to experience the same perfect storm of weather conditions that allowed such a large number to migrate up to northern Minnesota and that is not likely.

Watch Out For Wasp Nests

Jeffrey Hahn, Asst. Extension Entomologist

Now is a good time to take a close look for wasp nests around your home. They are getting large enough to be noticed but have not reached their peak size yet. Wasps can nest in a variety of locations. Some species commonly nest under eaves of homes, the branches of trees and shrubs, and similar open, exposed areas. They also commonly nest in the ground, especially in old rodent burrows, as well as wall voids, attics, and other hidden sites. If you see any kind of persistent activity of wasps in a particular location, take a closer look to see if there is a nest involved.

Jeff Hahn

Photo 1: Wasp nests can be found in the most unexpected places

One wasp, the European paper wasp, is interesting because of its ability to construct small nests in many different, unusual sites. Just in the author's backyard, they have been found nesting in the tail pipe of a unused van and inside an unused bird feeder. Paper wasps typically nest on the underside of horizontal surfaces. However, European paper wasps have the ability to construct their nests at angles. This wasp is also somewhat unique because while other wasps do not reuse their nests, they frequently reuse them which can result in larger than normal sized nests (for a paper wasp).

If you do find a wasp nest, the particular control you use will depend on factors, such as where the nest is located, how close to human activity it is, and whether the nest is out in the open or hidden. Click here for more specific information on controlling wasp nests.

Leafcurl Ash Aphids on Ash

Jeffrey Hahn, Asst. Extension Entomologist

This June has seen a lot of activity by leafcurl ash aphids, a type of woolly aphid, not only in the Twin Cities but also in a number of other areas in Greater Minnesota. Like other aphids, leafcurl ash aphids use piercing - sucking mouthparts to feed on the sap in the leaves. This feeding causes leaves to become tightly curled, puckered, and distorted. To verify leafcurl ash aphids, unroll the leaves. The aphids are a light green and no more than 1/8 inch long. They produce a conspicuous white waxy material that covers the aphids as well as the leaves.

Kim Sullivan

Photo 1: Leafcurl ash aphid. Note the curled leaf and the white waxy material

These aphids also produce a lot of honeydew. Honeydew is a sticky waste material because the aphids are not able to digest all of the sugars in the sap. Any objects under a leafcurl ash aphid infested tree can get coated with this substance. Later you might find sooty mold, a black fungus developing on the honeydew. Fortunately, light infestations of sooty mold causes little damage to plants.

These aphids were even reported as nuisances when they would fall down on people in their yards (which is not conducive for graduation parties and other outdoor activities).

Leafcurl aphids feed on the new growth that expanded this spring. Colonies last until mid-summer. Winged forms are produced which migrate to the roots of ash where they remain for the rest of the year. Leafcurl ash aphids have always been in Minnesota but have been infrequently noticed or reported over the last 5 - 10 years.

Although the damaged leaves are conspicuous, when you look closely, just a small number of leaves within a tree are actually affected by leafcurl ash aphids. Even the leaves that are distorted can still photosynthesize so there is very little risk to the health of ash.

While insecticides, such as imidacloprid and dinotefuran are effective against these aphids, they are rarely warranted to protect trees and are not suggested. Even if you kill the aphids, the distorted leaves will remain for the rest of the season. While this can affect the trees' appearance that is of small consequence compared to other problems, especially the risk of emerald ash borer

Amazing Leaf-Cutter Bees

Karl Foord - Extension Educator, Horticulture

I was walking through the Horticulture Display Garden at the University of Minnesota St. Paul Campus. A bee landed on the ground and disappeared. I got my camera but couldn't find the hole it had disappeared into, so I waited. In a few minutes the bee returned with a bit of leaf rolled under its abdomen and again disappeared down the now somewhat visible hole.

This was no leasurely entrance and exit from the hole. The time from seeing the bee approach the hole to disappearance was less than one second. It took less time for the bee to show at the top of the hole and exit. The bee exited headfirst so it had had enough room in the hole to turn around.

The bees that nest in this way are aptly named Leafcutter bees and are in the genus Megachile (Photo 1).

Karl Foord

Photo 1: Leafcutter bee (Megachile spp.) on Sea Holly (Eryngium planum)

They are identified by the hair on the bottom of their abdomen which traps pollen. They do not have a pollen basket like honeybees.

Photo 2 shows a leafcutter bee next to a honeybee to show the size difference.

Karl Foord

Photo 2: Honeybee on left, Leafcutter bee on right

I documented this event with a video:

Leaf-cutter bee building nest

The bee took between 45 and 60 seconds to leave the nest retrieve a leaf piece and return to the nest. Entry and exit events have been patched together and slowed down by 50%.

Sometimes even at half speed the bee moves too quickly to appreciate what is happening, so I made a collage of still photos of nest entry (Photo 3) and nest exit (Photo 4).

Karl Foord

Photo 3: Leafcutter bee entering nest with leaf material

Karl Foord

Photo 4: Leafcutter bee exiting nest and leaf cuts for nest building

I also wanted to know where it was getting its nest material. I found that leaves of Long leafed Speedwell Veronica longifolia had the characteristic holes created by the leaf cutter (Photo 4). Note that not all the leaf cuts are the same; oval pieces are used to coat the sides of the nest, and circular pieces close up the nest cells.

Other leafcutter nest sites are created in gaps between stones or bark, hollow plant stems or other preexisting holes. These bees do no real harm to plants in collecting leaf material, and they are good pollinators. Keep an eye out for them in your garden. They are a treat to watch.

Hawthorn Mealybug: An Interesting Insect in the Landscape

Jeffrey Hahn, Asst. Extension Entomologist

Hawthorn mealybug, Phenacoccus dearnessi, has been found infesting several hawthorns in Minneapolis. This insect is globular and red, although it will appear to be white as it is covered with a white waxy material. In addition to hawthorn, it can also attack mountain ash (an infested mountain ash was found adjacent to the hawthorns), cotoneaster, juneberry (amelanchier), and other plants in the rose family.

This is not a common insect in Minnesota. In fact in Minnesota the best place to find mealybugs is on greenhouse and house plants and not landscapes. Even our neighbors in Wisconsin and Iowa have not seen the hawthorn mealybug (so far). It is, however, found in northeast Illinois.

Whitney Cranshaw, Colorado State University,

Photo 1: Hawthorn mealybug

This insect colonizes the bark of twigs and small branches using its piercing sucking mouthparts to feed on the sap. Hawthorn mealybugs also produce a lot of honeydew, a sugary waste material as a result of feeding on the sap. Honeydew is shiny, clear or whitish in appearance and sticky. Honeydew can also lead to sooty mold, a black fungus that colonizes the honeydew. Hawthorn mealybug has the potential to weaken branches and cause dieback, although that has not been noticed on infested trees here so far.

Hawthorn mealybugs appear to have one generation per year. They mature in the late spring. Eggs hatch and nymphs are active by early summer. After feeding on leaves briefly, the nymphs move to twigs and feed in protected sites.

Because of the white waxy material that is present and the habit of the nymphs to feed in protected places, direct insecticide control can be challenging. However, if management is necessary, an application of a systemic insecticide, like imidacloprid and dinotefuran should be effective.

Blow Flies and Flesh Flies

Jeffrey Hahn, Asst. Extension Entomologist

Some people have discovered the sudden appearance of medium sized flies in their homes. Blow flies are iridescent green, blue, or coppery colored flies while flesh flies have dark colored bodies with three black stripes on their thorax and a checkerboard pattern on their abdomen. Both types of flies lay their eggs on dead animals and decaying garbage. The larvae are smooth, cream-colored, legless maggots that are carrot-shaped with the narrowest end by the head. When fully grown, they are about 3/4 inch long.

Jeff Hahn

Photo 1: Blow flies on animal remains

When a dead animal becomes trapped inside a home, e.g. inside a ceiling or wall void, and dies, it is not uncommon for it to attract these flies which lay eggs on the corpse. Eventually they turn into adult flies which can emerge into the home. It is also possible to see the maggots inside a home. As mature maggots wander away from their food source to less crowded sites to pupate, they can inadvertently move through light fixtures or other spaces and fall into the living space of a home.

These flies are generally harmless to people and property, although because of their unsanitary habits they do have the potential to spread filth-related diseases such as diarrhea and dysentery. On the plus side, they are helping us out by removing and recycling organic material.

A blow fly or flesh fly infestation will persist until the carcass is consumed. The most effective method to control them is to remove the food source, i.e. the dead animal. Unfortunately, this is usually not practical as the animal is typically trapped in an inaccessible place. Be patient and eventually the dead animal will be removed naturally by the maggots. The flies and the maggots will go away on their own once the food source is consumed. This generally takes several weeks to happen.

Click here for more information on summer flies.

The Eyes Have It

Jeffrey Hahn, Asst. Extension Entomologist

Jeff Hahn

Photo 1: Eyed click beetle

During June, some people encountered eyed click beetles, Alaus oculatus, an interesting and conspicuous looking insect. An eyed click beetle is large, about 1 - 1 3/4 inch long. The wing covers are black mottled with small whitish patches. What are immediately noticeable are the two eyespots on its prothorax (the area behind its head) which are velvety black surrounded by a whitish ring. Eyed click beetles are associated with decaying logs and stumps and are found in open wooded areas. Watch for and enjoy the adults during spring. This insect is harmless and just a curiosity.

Brace For Impact: Japanese Beetles Are Coming!

Jeffrey Hahn, Asst. Extension Entomologist

The moment many people have been dreading has arrived - Japanese beetle (JB) are starting emerge. It is not necessary to panic as they are not out in force yet. There have been a few individuals that have been found early (normally JB is not out until the first week of July). However, you know the rest are not too far behind. In fact with the recent rains, we could be seeing large numbers will probably emerge within a week or less.

JB is a pest because the adults feed on the leaves and flowers of many plants while the grubs feed on the roots of turf grass. If you have seen JB grub damage in the past, July is a good time to treat your yard. Use a preventative insecticide, like imidacloprid, after you see adults flying, about late June or early July this year. By the time eggs are laid and grubs hatch, about two to three weeks, the insecticide will be taken up by the grass and the young grubs will be exposed to it.

As the grubs get older they are less affected by preventative insecticides. It is still possible to control them with a curative insecticide, such as trichlorfon (e.g. Dylox). You can effectively treat JB with a curative insecticide until about mid-August. Remember to only treat the grubs if you are experiencing problems in your lawn. It is not effective to treat grubs to reduce the number of adults that are seen in your garden. Adult beetles are good fliers and can easily fly into your yard from the surround neighborhood.

Jeff Hahn

Photo 1: Japanese beetle damage on linden

You have a variety of options for managing the adults, including handpicking, low impact products like Neem and pyrethrins containing PBO, and residual insecticides, like permethrin and carbaryl (Sevin).

Another option is the use of a systemic insecticide, like imidacloprid (various trade names) and dinotefuran (Safari). They are easy to apply and are long lasting. They do not kill JB quickly but they do cause them to stop feeding with death coming later. One important drawback of these products is they are very toxic to bees. Avoid treating plants, like linden and roses, that are very attractive to bees. It doesn't matter that the trees and shrubs are not flowering at the time of application as these insecticides will be active for a year. Another important consideration is that it takes some time, especially for imidacloprid, for the tree to translocate the insecticide (3- 4 weeks for large trees). If you have plants that have been plagued by JB in the past, now would be a good time to treat them with a systemic so the insecticide can protect them before much damage is inflicted.

For more information see Japanese beetle management in Minnesota.

Karl Foord - Extension Educator, Horticulture

Swamp Milkweed (Asclepias incarnata) as you know is an important plant for Monarch Butterflies. The plant also produces significant amounts of nectar and thus attracts a host of other pollinators including various bees and ants (Photo 1).

Karl Foord

Photo 1: Milkweed flower (Asclepias incarnata)

On close examination the flower structure is bizarre. Typical corollas face backward (Photo 1), whereas prominent coronas fold to form a tube of sorts out of which a horn projects toward the center of the flower. The stamens have fused to form a cylinder around the pistil with a pink stigmatic surface in the center (Photo 2).

Karl Foord

Photo 2: Milkweed flower (Asclepias incarnata) close-up of unpollinated flower

Pollen has fused to form wings called pollinia which are connected by a dark pollinarium gland, the whole structure being called a pollinarium. You can see the wings protruding from the side of the fused staminal column (Photo 2). The strategy is for an insect to visit the plant looking for nectar and catch its leg on one of the pollinia wings which detaches from the plant and attaches to the insects leg. The insect carries the pollinarium to another flower where the horn may help in detachment placing pollen on the stigmatic surface.

Karl Foord

Photo 3: Milkweed flower (Asclepias incarnata) close-up of pollinated flower

I took many pictures hoping to find an insect with a pollinarium attached to its leg. Alas I did not find one. However, I did find pollinarium that had been transferred from another flower. They can be seen in Photo 3 where the top center section has three pollinarium and the top left section has two pollinarium where originally each had only one.

Megarhyssa, a Large Ichneumonid Wasp

Jeffrey Hahn, Asst. Extension Entomologist

A large wasp has been noticed in the landscape recently. This insect is a type of ichneumonid (ich-new-MON-id) wasp known as Megarhyssa (meg-a-RISS-uh). Megarhyssa is a reddish brown and yellow insect (another species is black with an orangish head) with a body length of about one and half inches long. That does not include it ovipositor which is another two to three inches long (that's up to over four inches total length!). In addition to the ovipositor, you will find two sheaths protecting it which sometimes gives the appearance that it has three 'tails'. Sometimes Megarhyssa is confused for other large sized insects, e.g. mayflies or dragonflies, so look closely to be sure it correctly identified.

Winnifred Williams

Photo 1: Megarhyssa ovipositng in a tree. Note the long ovipositor

Ichneumonid wasps are parasitic upon other insects. Megarhyssa is a parasite of horntails. Horntails attack dying or recently dead hardwoods, such as oak, maple, birch, and elm. With her long ovipositor, Megarhyssa can drill 1/2 inch or more into the wood to deliver an egg into the horntail larva. When people see this ichneumonid wasp ovipositing into a tree, they believe that it is attacking it. Of course, this is not true. Once the egg hatches, the Megarhyssa larva slowly feeds on the horntail, eventually killing it. After it matures into an adult wasp, it emerges from the tree.

Despite her large size and her menacing ovipositor, ichneumonid wasps, like Megarhyssa, pose no threat to people. They are not aggressive and avoid us when possible. It is possible that if someone handled a Megarhyssa, she could try to jab you with her ovipositor if she felt threatened but she could only inflict a minor wound at best.

If you see Megarhyssa, just ignore her. Any that you find will go away on their own in a short time. It is never necessary to treat them with an insecticide.

Earwigs: Pests of Homes and Gardens

Jeffrey Hahn, Asst. Extension Entomologist

Jeff Hahn

Photo 1: Earwig found outdoors in garden. Note the second earwig hiding in the crack between the pavers

Earwigs season is beginning as immature nymphs are starting to turn into adults. They are pests when they enter homes, often in large numbers, and become bothersome. They can also damage flowers and other plants in your garden. Earwigs can be challenging to control, especially when they are abundant. Here are some steps you can take to minimize them on your property.

Regardless of whether you are dealing with them in your home or garden, you can reduce their number by using traps in the landscape. Use rolled up newspapers cardboard tubes, or similar objects and set them up outside where you are see earwigs. They will crawl inside these objects by early morning in order to hide. You can then shake them into a pail of soapy water to dispose of them.

Moisture management is also important. Minimize excess moisture by keeping irrigation equipment in good working order. If you need to irrigate your garden, water less frequently but more deeply so the soil remains more dry, making it less conducive for earwigs.

Phil Pellitteri

Photo 1: Earwig found indoors. Has any friends joined him?

If you are having a problem with earwigs in your garden, you can supplement your non-chemical efforts with an insecticide. You can treat the mulch with insecticide, e.g. lambda cyhalothrin, or put out chemical baits, e.g. carbaryl, around the affected plants. You can also treat affected plants directly with any one of a variety of garden insecticides, e.g. permethrin.

If you are having a problem with earwigs coming into your home, check around the outside of your home and seal or repair any openings or gaps you find that allows earwigs to get inside. Check particularly around the foundation, windows and doors. Also examine where siding and foundation meet as well as the areas around water facets and vents. You can supplement this with an insecticide application around the exterior the home, e.g. permethrin or cyfluthrin.

What Kind of Moth Was That?

Jeffrey Hahn, Asst. Extension Entomologist

Terry Straub

Photo 1: Hummingbird moth (hummingbird clearwing)

There has been a variety of curiosity questions received recently about interesting moths. Several people have reported seeing hummingbird moths (also called hummingbird clearwing), Hemaris thysbe and/or bumble bee moths (also called snowberry clearwings), H. diffinis, in their gardens. These moths, a type of sphinx moth, are daytime flyers. They have relatively small, stout bodies and their wings are mostly clear, lacking scales on them. They fly like hummingbirds, deftly hovering and flying around flowers as they visit blossoms for nectar. 

You can distinguish between them as hummingbird moths are little larger with a wingspan of about two inches. They have a yellowish body and the borders and veins of the wings are reddish brown. Bumble bee moths are a little smaller with an average wingspan of about 1 ½ inches. They have a yellow and black body with black veins and a narrow black band on the edge of the wings.

Another sphinx moth that has been noticed lately is the whitelined sphinx moth. It is a large moth with a wingspan between 2 and 3 ½ inches. The first pair of wings are dark colored with a large white stripe running from the wingtip diagonally to the base of the wing and six smaller white lines crossing it. The second pair of wings is dark with a pinkish band. This moth is active at dusk as well as at night. It also flies around flowers like a hummingbird.

Terry Curtis

Photo 2: Whitelined sphinx moth

Later their larvae may be found in gardens feeding on evening primrose, grape, plants in the Rosaceae (rose family), and other herbs and woody plants. This caterpillar grows to be as large as three inches long with a distinctive horn on the end of its body. Most are green with black stripes and yellow and orange markings, although some are mostly black with some greenish yellow. 

Two giant silkworm moths may be seen now. Both species overwintered as cocoons and started to emerge during late spring. The cecropia moth is reddish brown with a wingspan of five to six inches. The polyphemus moth is a brown moth with a large blue and yellow eyespot on each hind wing. They will produce caterpillars that will become large and conspicuous by late summer and early fall as they feed on the leaves of a variety of hardwood trees.

The cecropia caterpillar grows up to 4 inches long. It is light green with a double row of reddish orange knobs (turbercles) on the thorax behind its head. There are also series of smaller yellow and blue knobs (turbercles) on the abdomen. The

Jeff Hahn

Photo 3: Cecropia moth

polyphemus caterpillar grows to be about 3 1/2 inches long when fully grown. It is a pale green with sparse long hairs along the top and sides of the abdomen. 

Forest Tent Caterpillars at End of Feeding

Jeffrey Hahn, Asst. Extension Entomologist

If you are thinking about treating forest tent caterpillars, check their size because the odds are it is too late to treat them any more this year. If they are between 1 3/4 - 2 inches long, they are either finishing or are done with their feeding. Forest tent caterpillars, sometimes called (incorrectly) armyworms have been active since mid to late April and typically feed 5 - 6 weeks. The best time to treat them is when they are half full grown size, or about one inch long.

Gail Felton

Photo 1: Nuisance forest tent caterpillars crawling on home

Older larvae can cause problems by coming down from trees and wandering around looking for food. Sometimes they can severely damage nearby plants, including those in gardens. Other times, they are annoying when they crawl onto homes, sidewalks, decks, patios, outdoor furniture, and other objects. They may even pupate on homes and other things, further being nuisances.

They are difficult to deal with, especially when they are abundant. You can try to create a barrier with an insecticide, such as permethrin (be sure any insecticide you use is labeled for the area or plants you intend to treat). Otherwise use physical removal (avoid crushing the caterpillars if possible when they are homes). It is likely you will need to be persistent as effective physical removal is often time consuming. 

Click here for more information on forest tent caterpillars.

Cutworms Gone Wild

Jeffrey Hahn, Asst. Extension Entomologist

Many parts of Minnesota experienced large numbers of adult cutworm moths recently. However, it was not so much the moths that were noticed as were the many eggs that were laid on homes on windows, siding, soffits and other places. Clusters of eggs were reported from the Twin Cities up to northern Minnesota, especially in the northeastern part of the state. Some towns found that essentially all buildings had at least some eggs on them. One resident said he found as many 15 clusters of eggs on his home. Wisconsin also experienced a similar phenomenon with cutworm eggs found in much of the northern half of their state.

Insect eggs are often challenging to identify, especially to species. While it was fairly easy to diagnose the eggs as belonging to a moth, it wasn't until someone was finally able to catch the culprit in the act of laying eggs that the species could be identified as a variegated cutworm. Variegated cutworms are native to Minnesota but it is very unusual to see such large numbers, especially in northern Minnesota where they are rarely seen.

Mike Misk

Photo 1: Variegated cutworm eggs on house

An individual variegated cutworm egg is tiny, about 1/50th in diameter. It is hemispherical with many ridges and is whitish or yellowish at first, before turning brown. There can be hundreds of eggs in a single cluster. Once they hatch, they are small and dark. As they grow larger, they are brownish to black with four to five yellowish diamond-shaped spots on the top of the body starting at the head. You may also see a dark-colored 'W' on top of its body near the posterior. They can be up to two inches long when fully grown.

You might expect that with so many eggs being laid that this would mean an increased problem with cutworms in gardens and agricultural fields. So far this has not been the case. Still, if you noticed clusters of eggs in your area, monitor your garden and watch for signs of cutworms, i.e. young plants cut off at ground level. The eggs laid on homes are little risk to gardens, as the caterpillars are very likely to die before they can move and find susceptible plants.  Click here for more information on cutworms, including management.

Watch Out for These Insects

Jeffrey Hahn, Asst. Extension Entomologist

Insects are out in full force in gardens and yards this spring. Are any of these pests at your home?

Aphids are small pear-shaped, soft-bodied insects. They have been reported on roses and red elderberry this spring so far, but will feed on a wide variety of herbaceous and woody plants.

They feed on plant sap with a long, needle-like mouthparts. Plants typically do not exhibit noticable symptoms when infested by small to moderate numbers of aphids, although large numbers can cause wilting and loss of plant health. There are many natural enemies to help keep aphids under control, especially ladybird beetles. If you are dealing with larger numbers of aphids, try spraying them off with a hard stream of water.
If you need a low impact insecticide, consider insecticidal soap or horticultural oil.

Fourlined plant bugs have just started to hatch.

They feed on a wide variety of herbaceous plants as well as shrubs and fruit. Look for reddish nymphys now (Photo 1);

Jeff Hahn

Photo 1: Fourlined plant bug nymph and damage

eventually they mature into greenish yellow insects with four black stripes. When fourlined plant bugs feed, they produce small, round sunken lesions on the leaves. Large numbers can reduce plant health, although in many cases only smaller numbers are present which cause cosmetic damage.

When practical, crush nymphs that your find; you can also spray them with insecticidal soap. You will need a residual insecticide for the adults.

See also,

There have been several species of sawflies reported recently.

European pine sawfly feeds on the old needles of pine especially mugo pine.

Columbine sawfly feeds on the edge of the leaves of columbine, sometimes feeding until there is nothing left but the midrib.

Roseslug causes a different type of damage on roses. They feed on one layer of leaf tissue, feeding between the veins. At first, this damage looks kind of lacey, as if something sucked the green out of the leaves, Later these damaged areas turn brown.

Sawflies are no more than 1 inch long when fully grown (foseslugs are just 1/2 inch long), so look carefully for them on your plants.

Once your find them, you can use insecticidal soap, horticultural oil, spinosad or a residual insecticide.

Forest Tent Caterpillars Are Out Now

Jeffrey Hahn, Asst. Extension Entomologist

Did you have a problem with forest tent caterpillars (FTC) last year? If you did, expect to see them again soon as they have started to hatch during late April. You can recognize these caterpillars from their blue and black body and white footprint or keyhole shaped spots on their back. Despite their name, FTC do not construct conspicuous webs. If you find a large tent in a tree this spring, that is from eastern tent caterpillars.

Jeffrey Hahn

Photo 1: Forest tent caterpillar and damage

FTC are primarily a problem because they feed on the leaves of trees and shrubs, especially aspen, birch, oak, and linden/basswood. If they are abundant and their normal food is in short supply they will crawl down trees and also feed on fruits, vegetables, and flowers. They can also become nuisances when they wander around looking for sites to pupate (which has earned them the nickname 'armyworms'). This can lead them to crawl onto nearby buildings and other structures.

Populations of FTC are cyclical, with periods of few and increasing numbers of FTC lasting about 8 - 13 years. Eventually these increasing numbers hit outbreak numbers which lasts about three to four years. FTC populations in the Twin Cities, though, appear to be less cyclical.

Fortunately, healthy, mature trees can tolerate severe defoliation, even in several consecutive years. Young and unhealthy trees are more susceptible to injury and should be monitored closely for the potential need to treat. There are a variety of residual insecticides that you can use if you want to protect your plants. Consider using products that have a low impact on the environment, such as Bacillus thuringiensis, spinosad, and insecticidal soap. Bacillus thuringiensis is a particularly good product if the tree is flowering since it will not harm visiting honey bees.

There are also insecticides available to protect garden plants, including food crops. Be sure to check the label to be sure the particular product you want to use is cleared to treat the plants you wish to protect.

Clover Mites in Homes

Jeffrey Hahn, Asst. Extension Entomologist

Some people have been experiencing clover mites around their homes recently. Identification is important as they could be misidentified as other types of mites or even very small ticks. Clover mites are about the size of a pinhead (about 1/30th inch long) and are reddish or brownish in color. They have a round body and eight legs with the first pair of legs particularly long. People find them on the outside of their homes as well as around windows.

Rayanne Lehman, PA Dept of Agriculture,

Photo 1: Clover mite

Clover mites feed on grass and clover during summer (they are not pests on these plants). They take shelter in and around buildings during the fall. You might see them then but they are much more commonly noticed during spring. They can potentially occur in very large numbers around buildings and have no problem getting inside, especially around windows, because of their small size. They love being in the sun and are most common on the south sides of homes. Fortunately, clover mites are not harmful to people or our property. However, they can stain surfaces if they are crushed.

If you are not seeing many, the best bet is physical removal. Use a vacuum cleaner or gently wipe them up with a damp cloth to help minimize crushing them. Clover mites are a temporary problem that will go away on its own when the weather become warmer.

If you having a problem with large numbers entering your home, you can treat the foundation to deter them with an insecticide containing bifenthrin (be sure it is labeled for spraying the outside of homes). You can also consider hiring a professional pest control service to treat your home's exterior.

If you deal with this problem most years and are looking for a more sustainable approach to managing them, you can try maintaining a barrier of clean, bare soil around your home, i.e. free of grass and leaves. Clover mites generally do not cross such a barrier. This barrier should be about 18 - 24 inches wide. If you do have annuals, perennials, or shrubs planted in this zone, have them far enough apart so the clover mites can not easily bridge across this barrier. Landscape rock apparently is not enough of a deterrent to keep clover mites away from buildings.

Karl Foord - Extension Educator, Horticulture

While exploring the Minnesota Landscape Arboretum I encountered Dr. Stan Hokanson the woody plant breeder in the Department of Horticulture Science. He introduced me to the Clove Currant (Ribes odoratum). The odoratum nomenclature is well deserved. Clove Currant give off a very pleasant spicy fragrance hinting of clove and alspice (Photos 1 and 2). The plant has yellow flowers and a corolla long enough to restrict its pollinators to those with long tongues like bumblebees (Photos 3 and 4).

Another tree with fragrant flowers is the Korean crabapple (Malus bacatta jackii) one of the earlier flowering crabapples. The flowers are being visited by native bees (Photos 5 and 6).

Karl Foord

Photo 1: Clove Currant (Ribes odoratum) flower close-up

Karl Foord

Photo 2: Clove Currant (Ribes odoratum) flower

Karl Foord

Photo 3: Bumblebee showing long tongue required to reach nectaries on Clove Currant

Karl Foord

Photo 4: Bumblebee pollinating Clove Currant

Karl Foord

Photo 5: Native bee (Andrena ssp.) on Korean crabapple (Malus baccata jackii)

Karl Foord

Photo 5: Native bee on Korean crabapple (Malus baccata jackii)

Overwintering Insects in Homes During Spring

Jeffrey Hahn, Asst. Extension Entomologist

Throughout March, people have been having problems with nuisance insects in their homes, especially cluster flies, boxelder bugs, and (multicolored Asian) lady beetles.  Fortunately, these insects are harmless, although they can be annoying, especially when a lot of them are present.  Here are a few things to keep in mind when dealing with these insects.

First, it is important to know that these insects are not reproducing indoors.  Because they emerge from their hiding places periodically throughout the winter and early spring, it appears they are laying eggs and their offspring are emerging.  In fact, all of the insects you see now entered your home last fall.  They hibernate in balls or clusters in wall voids, attics, and similar areas.  As the temperatures warm, the insects in the outer layers become active first and then emerge into the living quarters of the home, explaining why they do not all become active at the same time.

Gail Felton

Photo 1: Multicolored Asian lady beetles

Because they are emerging from hidden sites, it is not practical to treat them to prevent their emergence.  Once they are out in the open, your best bet is physical removal, such as vacuuming.  Eventually, all of these overwintering insects will become active and move away from their overwintering sites.  Fortunately for those trapped in homes, they are short lived

To minimize these kind of problems in the future, it is important to treat these insects in the fall as they are first trying to enter your home.  This is a two pronged approach.  First it is important to inspect the outside of the home during summer and seal spaces and gaps that may be used by these insect to get inside.  This should be followed up with an insecticide application in the fall, just as these insects are trying to get inside.  It is not possible to prevent all nuisance insects from entering into a home, but you can reduce the number that do causing fewer problems later during the winter and spring.  You can find more information here on cluster flies, boxelder bugs, and lady beetles.

Some Questions About Japanese Beetles

David Cappaert, Michigan State University,

Photo 1: Japanese beetle grub

Jeffrey Hahn, Asst. Extension Entomologist

There have been a lot of questions concerning Japanese beetles (JB) as we go into the 2012 growing season.  JB has been increasing in numbers over the last four or five years, especially in the Twin Cities area, although JB are also starting to be found more commonly in other areas of the state as well.  They can be challenging to control and people will take any steps they can to reduce their numbers in their gardens and yards.

The first question people ask is how bad are JB going to be this year.  There isn't an easy answer to that question and it undoubtedly will vary according to where you live.  If JB was abundant last year, there is a good chance they will be common again this summer.  However, a factor that can have an impact on JB numbers is soil moisture.   The eggs and the young grubs have a harder time surviving in dry soil so if dry conditions exist when JB are laying eggs, that can reduce the numbers of adults that are seen the following year.  Of course, if the turf area is well watered, that will make it easier for JB to survive.

It is difficult to determine what role the winter weather had on JB populations.  Although the mild temperatures favored JB, the lack of snow cover could have been potentially detrimental to them.  The early spring we have been experiencing should not have any effect on JB numbers.  However, expect them to emerge earlier than normal.  In a typical season, JB emerge around the 4th of July.  If the weather holds, the adults could be active as soon as the 3rd or 4th week of June.

And speaking of the early spring, people are wondering whether they can still treat JB grubs this spring or whether it is too late.  An important to factor to first consider is whether your primary goal is to control the grubs, because you are seeing damage in your turf, or the adults because of damage they have done to garden and landscape plants.  If your aim is to reduce the adults by controlling the grubs, you can save yourself the effort as this is not effective.  The adults are mobile and can easily fly in from areas outside your property. 

If you are finding turf damage due to JB grubs, and if you have had a lot of adults on your property look carefully for this, then the best time to treat for grubs is in July.  If you are going to use a preventative, such as imidacloprid (e.g. Merit), then you should be treating your turf when you first see the adults flying.  About two to three weeks after the first adults have emerged, JB eggs are hatching.  Preventative insecticides are most effective against the first instar larvae but not the older second and third instar larvae so the timing is critical. 

If JB grubs are not treated then, it is still possible to control them with a curative insecticide, such as trichlorfon (e.g. Dylox).  You can effectively treat JB with a curative insecticide until about mid-August.  By spring, the grubs are too large to effectively treat them.

Winter Cutworm

Jeffrey Hahn, Extension Professor and Asst. Extension Entomologist

Marge Kelley

Photo 1: Winter cutworm

There have been a number of reports this winter of caterpillars active on top of the snow. This mystery caterpillar is an exotic moth known as Noctua pronuba, commonly called the winter cutworm or (large) yellow underwing. The first report this season came from Itasca county in December. Then on New Years day, after we had a light snowfall, there were several reports of this insect in Washington county in the eastern Twin Cities area (note: there were also a number of reports across the border in northeast Wisconsin). One person said they found about 30 of these caterpillars while another said they saw as many as 60 - 70 at a time.

There is a precedent to seeing insects outdoors during the winter. Insects, including snow flea, snow scorpionfly, and small winter stonefly, are know to tolerate colder temperatures and can be found on top of the snow during winter. Now we can add winter cutworm to this list.

This caterpillar overwinters as a large larva. It has a smooth, hairless body and can be as large as three inches when fully grown. It is colored light to dark brown with a series of black dashes running down its back. It also has two black bracket-like markings on its head. As an adult moth, it has brownish forewings and bright orangish yellow hind wings with a black band near the margin of the wing.

Originally from Europe, winter cutworms were first found in North America in Nova Scotia in 1979. They are now generally distributed throughout the northeastern U.S. They are also found in the upper Midwest as well as a variety of other states, even California. They were first noted in Minnesota sometime in the late 1990's from moths collected at black light traps in Lamberton (in Redwood county in southwest Minnesota). It is likely there were present in other counties at that time and they are probably now generally distributed throughout the state. Interestingly, this is the first time that these caterpillars have been reported during the winter.

This insect feeds on a wide variety of agricultural and garden plants. Despite the fact that winter cutworm has been in Minnesota for 12 - 14 years, it has not been reported as a problem in agricultural fields. It is possible for home gardeners to find this insect but it is generally not expected to be a significant problem. Look for them right away in the spring and then again during mid to late summer and into the fall. If you do find winter cutworms, just treat them like any other cutworm.

An Interesting Insect Found Indoors

Jeffrey Hahn, Asst. Extension Entomologist

Jeff Hahn

Photo 1: Soldier fly, Ptecticus trivittatus

Many people are familiar with boxelder bugs, multicolored Asian lady beetles, cluster flies, and other nuisance insects that can be found in homes. But occasionally less familiar insects are found inside. On one such occasion, a homeowner reported finding a lot of wasps nesting in her home. In fact, she had identified them from the internet as Cerceris fumipennis.

This wasp species is a solitary wasp in the family Crabronidae. It has gained fame recently as a method for detecting emerald ash borers (EAB). This native ground nesting wasp hunts buprestid beetles, including EAB, which it paralyzes and carries back to its nest to feed its larvae. Location of a nest with captured EAB indicates the presence of EAB in the area. More information on Cerceris wasps can be found here.

This wasp's status is unclear in Minnesota and nests have not been discovered so far. Ultimately, you would not find this wasp indoors in the winter as they do not overwinter as adults.

A sample of insects was requested from the homeowner with the expectation being that paper wasp queens, Polistes spp., which overwinter gregariously in homes would be found. It was therefore quite a surprise to find that not only were the insects not paper wasps, but were instead flies. A run through the diagnostic keys identified them as soldier flies (family Stratiomyidae). These flies are typically black and yellow insects that can appear to be wasp- or bee-like.

A run up to the museum, and with the help of John Luhman, the soldier flies were identified specifically as Ptecticus trivittatus. This is a species that is particularly associated with composts. The conclusion was that these soldier flies most likely originated from a compost nearby in the neighborhood and they found their way to this home in which to overwinter. There had a mild stretch of weather when the homeowner first noticed the flies which would have been sufficient to cause overwintering insects to become active. There are other flies, such as cluster flies and face flies, that overwinter in structures so this made sense.

The homeowner kept insisting that these insects were nesting in her home. She was continuing to see consistent numbers of them; at one point she was seeing as many as 20 - 30 at a time. She eventually asked whether these flies could be associated with composts. They had brought a worm compost box indoors so the worms would not freeze. It was in a plastic tub with a cover but there were small air holes. She wondered whether the soldier flies could be in the compost. That of course was the source of the problem and why they were seeing such persistent numbers. The adult flies would be short-lived but to put an end to the problem it was important to erect some kind of screening so the flies could not escape.

A good example of how the identity and biology of an insect has a direct impact on its management.

Karl Foord, UMN Extension Educator

I often see recommendations to use the pesticide with the least impact when controlling pests. However, prior to spraying every effort should be made to avoid pest outbreaks by using the best management practices for a particular crop. For example, most fungi need a period of wetness for their spores to germinate. Managing systems to permit maximum airflow reduces drying time on leaves and reduces the opportunities for fungal spores to germinate.

For the purposes of this article let's assume that all best efforts were made and a spray as the last resort was required. How would you go about choosing the one with the least impact? The first question might be impact on whom, with the second being how one would measure such impact. At a University of California Davis website a series of pesticides is listed. Each pesticide is rated according to its impact on aquatic live, beneficial insects, honeybees, and humans. The human impact is separated into acute and long term impacts. Acute being what can happen to you today, and long term being what can happen over a number of years due to continued exposure at lower dosage rates.

Each chemical is given a potential hazard rating based on a series of other documents and warnings on the chemical's label. These are complicated but can be accessed at the website previously mentioned. The ratings range from no risk, no known risk, and very low risk to very high risk or no data available. For those pesticides labeled for strawberry, the impact information has been consolidated into a table where the materials have been ranked from lowest risk to those of highest risk (table 1). For example if you encountered slugs (mollusks) in your strawberries, the less impactful of the two active ingredients would be iron phosphate and not metaldehyde. So looking for a product with this as the active ingredient would be the first choice.

If you encountered tarnished plant bug in your strawberries, you would want to choose an insecticidal soap as a first choice over malathion. If you were forced to go to malathion you would realize that you would want to avoid any situation where the spray could get into surface water. You would also want to be particularly sensitive beneficial insects and honeybee pollinators and not spray when they are active, most likely after dark.

This table should permit you to select the least impactful chemical, and to apply it in a manner producing the least impact through an understanding what organisms were at risk from the application.

Karl Foord

Moth Flies in Homes

Jeffrey Hahn, Assistant Extension Entomologist

Jeff Hahn

Photo 1: Moth fly

Not all small-sized flies that are found in homes are necessarily fruit flies. Another common type are moth flies, also called drain flies. These flies are about 1/8th inch long (or a little less) and are dark-colored with many hairs which gives them a fuzzy, moth-like appearance. They have leaf-shaped wings that are often held roof-like over their bodies (they are sometimes also held flat). If you look closely, you may be able to many parallel longitudinal veins in the wings.

Moth flies can be present anywhere in a home, especially in bathrooms, basements, and kitchens. These flies lay their eggs in moist, organic matter where the larvae, small, slender, legless insects, feed on decaying organic matter, fungi, algae, and similar material. They are commonly found associated with the gelatinous film found in sinks, shower and bathtub drains, and similar places. Moths flies can also be associated with sewage from sewer line breaks. Moth flies are primarily a nuisance because of their presence. They don't bite people but they can potentially be a mechanical vector of disease because of their association with filth.

The best control of moth flies is to remove the source of the infestation. You can not eliminate a problem by just spraying the adults that are out in the open, First check drains and basins for the presence of an infestation. If you are not sure, place some tape over the openings (sticky side down); flies will get stuck on the tape as they try to fly out. If you suspect a sewer line break under a floor or slab, it may be necessary to break through the floor or concrete to verify this.

If you are dealing with a drain, you need to remove the gelatinous gunk that has accumulated. You can do that by taking a brush with stiff bristles and physically removing it. Another effective option is to use biological drain cleaner which breaks down and removes he organic material. However the use of hot/boiling water, bleach, and chemical drain cleaners is not effective. Attempts to try to drown the larvae is difficult and is unlikely to be successful. If you are dealing with sewage from a broken pipe, it is critical to fix the break and remove the sewage and any contaminated soil that is present.

The Beneficial Challenge

Karl Foord, UMN Extension Educator

Do you actually see things that you do not recognize? I was hunting for agates near Custer, South Dakota and went through a great agate field and picked a number of nice specimens. I then visited a rock shop and was introduced to the prairie agate which I had not seen in any of the rock books. I went back to the agate field and found quite a few prairie agates. I had been in that field earnestly searching for agates before and did not even see these types until pointed out at the rock shop. This begs the question, can you be looking right at something and not see it or rather not recognize it for what it is? It is not that your eyes did not see it but rather your brain was not ready to discern.
This brings me to the subject of beneficial insects in the garden. Have I not seen them because I did not know what I was looking for? As I look forward to next year's gardening, I want to put the idea of discovering more beneficials at the forefront of my mind. To aid the process I would like to be able to see what it is that I am looking for. As advanced responsible gardeners I think we have an obligation to recognize the dynamics at work in our gardens. To this end I offer the following challenge: how many beneficials will you be able to see and identify from your garden in 2012?

What follows is a gallery of 8 beneficial insects with pictures of their mature and immature stages. Also included is a table showing the types of insects on which they prey.

Please click here for the pdf of the gallery: Beneficials.pdf

The Appeal of Integrated Pest Management (IPM)

Karl Foord, UMN Extension Educator

Green lacewing larvae searching for prey on a yarrow flower.

The goal of IPM is to prevent unacceptable levels of pest damage through the use of pest biology and environmental information. It seeks a solution that poses the least possible risk to people and the environment.

The great appeal of IPM is the understanding of the biological systems at play in the garden and the degree one needs to understand them in order to effectively use IPM strategies. This requires a certain knowledge and skill set. One needs to be able to identify the key insect and disease pests and the types of damage they inflict. One needs to understand the biology of these key pests and how climate influences their behavior. It is also important to understand the natural balances that exist in your garden ecology and to be able to identify beneficial organisms that are a part of that balance. The last item is to understand the use of various chemicals and their effects both direct and indirect. This is understandably quite a challenge. Among the many appealing aspects of gardening, one of them must be its challenges.

Most organisms living in your garden are benign in terms of our perspective of fruit or vegetable production. A few are labeled pests because they conflict with our goals, and a few are labeled beneficials because they tend to attack the pest organisms or because they aid in pollination and assure fruit set. Beneficial fungi and bacteria help plants absorb nutrients from the soil in the same way certain strains of E. coli help in the digestion of our food. However, consider the dilemma of labeling a yellow jacket that preys on caterpillars in the summer and feeds on ripe fruit in the fall.

IPM strategy begins with avoidance of the pest problem itself through use of pest-resistant varieties and cultural systems. For example, most fungi require leaf surfaces to be wet for a certain amount of time at a certain temperature for their spores to germinate. Cultural systems that reduce the opportunity for fungal populations to get established include: 1) proper selection of planting site, and 2) planting systems to reduce the time that leaf surfaces remain wet. Most fungal spores are omnipresent waiting for the right climatic conditions to grow, and by eliminating those microclimate conditions in our gardens we are using IPM strategies.

Some situations cannot be avoided by cultural systems and require monitoring of the plants by scouting for the presence of insects and disease. IPM recognizes that the garden exists within an ecosystem and as such there is a dynamic flux between predator and prey insect species, as well as a flux of fungal and bacterial presence based on temperature and moisture conditions.

Lady beetle larvae attacking a winged aphid on cotoneaster leaf.

The elimination of all insects through the use of a broad spectrum insecticide provides the opportunity for the fast reproducing prey species to bounce back and become an even bigger problem, or requires implementation of a time based spray schedule. The IPM strategy is to monitor insect levels and tolerate the presence of pest species as long as it remains below a threshold level. In commercial systems this threshold level is an economic level based on the cost of control materials and their application. For the home gardener this is probably not an economic number but rather an acceptable control point based on the expectations of harvest quality and quantity.

An insect example

Tarnished Plant Bug (Lygus lineolaris) is an insect whose nymph stage feeding can cause significant damage to strawberry fruit creating misshaped "button berry" fruit. In a commercial setting the nymphs would be sampled by walking through a field at 5% bloom and tapping blossom clusters against a white pan looking for the small green nymphs moving across the pan. If 25% of the 20 or more blooms tested have nymphs, the commercial action threshold has been reached and the grower should take action. This sampling would be conducted every few days to keep a close view of the pest situation.

For the home grower depending on the size of your planting, a pan of soapy water could be used instead of a white pan and all blossoms could be tapped with bugs falling into water and drowning. This would certainly reduce the population of tarnished plant bug and might reduce it below your threshold level. Also the plants could be examined for predators of the tarnished plant bug such as other true bugs "damsel bugs" or nabids (Family Nabidae), and big-eyed bugs (Geocorids), ladybird beetles, spiders, and parasitic wasps. Seethe following URL with descriptions of beneficial insects3:
This would be an example of physical removal of the pest as opposed to chemical.

A Disease Example

The use of a fungicide is based on weather conditions and the fungus in question. Leather Rot (Phytophthora cactorum) is a fruit disease of strawberries that is best managed by judicious use of straw mulch. "Straw mulch can reduce fruit diseases better than fungicides."1 Both Gray Mold (Botrytis cinerea) and Anthracnose (Colletotrichum spp.) overwinter on strawberry leaf litter and spores are transferred to flowers by splashing dispersal in heavy rains. If the temperatures are optimal the spores will germinate. Gray mold is a problem when plants are flowering whereas Anthracnose is a problem when the plants are fruiting. The IPM approach to these diseases involves use of straw mulch to reduce splash effects, removal of leaf litter as a source of disease material mostly in the renovation process2, and use of fungicides if weather conditions are optimal for fungal development.

The more you look into IPM, the more the world seems to expand.

Integrated Pest Management Manual for Minnesota Strawberry Fields Minnesota, Department of Agriculture, September, 2007.

Strawberries for the Home Garden

Field Guide for Identification of Pest Insects, Diseases, and Beneficial Organisms in Minnesota Strawberry Fields.

Further references

Managing Pests in Landscapes and Homes - A Homeowner's Guide to IPM in Minnesota

Fruit Flies

Jeffrey Hahn, Asst. Extension Entomologist

Jeff Hahn

Photo 1: Fruit fly

Fruit flies are particularly common in homes during fall. These flies, Drosophila spp., are about 1/8th inch long with a tannish body, and a dark-colored abdomen. An easy way to identify fruit flies is by their bright red eyes. However, their eyes do appear darker after they are dead and may not be as distinctive. Be careful, not every small-sized fly you encounter is automatically a fruit fly. Moth flies, phorid flies (also called humpbacked flies), and fungus gnats can also be common in homes. It is important to know which fly you are seeing because control will vary depending on which fly is present. If you have any doubts as to which fly is in your home, have an expert identify it for you.

Fruit flies can potentially be carried into homes in fruits and vegetables or they could fly in from the outside. Once in homes, they are attracted to fermenting and souring smells, e.g. around garbage containers and produce that is starting to become overripe. Fruit flies lay their eggs in a wide variety of sites as long as they are moist, contains fermenting organic matter, and are in reasonably undisturbed places.

You can help prevent fruit flies by eating fruits and vegetables while they are fresh or keep them refrigerated; do not allow produce to sit out and become overripe. Also, keep the inside of garbage containers clean from food residues. Rinse bottles and cans that you recycle and remove recyclables on a regular basis. Don't forget to periodically clean recycling containers to prevent a build-up of food residue. Remove garbage in tied plastic bags on a regular basis.

If you find you have a persistent problem with fruit flies, the most effective, permanent control is sanitation, i.e. eliminate their food source. Fruit flies are commonly found infesting overripe fruits and vegetables like bananas, tomatoes, potatoes, and onions. Also look for them around soft drink, wine, and beer bottles and cans that are being saved for recycling as well as in the recycling container itself. Another common site is trash containers especially when they are lined with plastic bags (look between the liner and the container). Remember that the source of the infestation may not be where the adult flies are found.

Fruit flies, however, will take advantage of a wide variety of different food sources and there are also plenty of unusual sites where you may discover fruit flies. You may need to be a detective and be imaginative to determine where they are coming from. In one case, fruit flies were infesting a tea maker after tea was brewed but was not cleaned out before it was put away. In another instance, they were found in rotting osage oranges (non-edible fruit that are purported to repel insects, spiders, and rodents) that were left out and forgotten. Remember that fruit flies are found in moist, undisturbed places where fermenting organic material is found.

Some people are tempted to spray fruit flies with an insecticide. While that will kill the flies you see, it is not a long term solution and more will return. Just spraying adults doesn't have any impact on the source of the infestation and the larvae that are developing. As long as a food source still exists, adults will continue to be present.

Fruit fly traps (either store bought or homemade) generally do not eliminate fruit flies. While you may capture some individuals, like spraying, it is difficult to catch them fast enough to actually eliminate them. However, you could use traps to help narrow down where infestations are located. By placing traps in every room, the trap with the most fruit flies usually indicates approximately where the problem can be found.

Fall Webworm

Jeffrey Hahn, Asst. Extension Entomologist

Jeff Hahn

Photo 1: Fall webworm feeding on black walnut

Fall webworm, Hyphantria cunea, is a web building moth that is common from mid to late summer.  It is yellowish or greenish with long, fine white hairs with two rows of black spots down its back, growing to about one inch long when fully grown.  However, an easier way to identify fall webworm is from the silken webbing that covers the ends of branches where the caterpillars feed in nonsocial groups.  These caterpillars feed on the leaves of over 100 different species of deciduous trees and shrubs, including black walnut, birch, ash, crab apple, elm, and maple.  

Fortunately, fall webworm normally has little impact on the health of large, vigorously growing, well-established trees (it is possible that small trees or shrubs can be completely defoliated in one season and could be injured).  Fall webworms are usually no worse than an eyesore because of the webs they construct, making management unnecessary.  This is especially during late summer as this feeding has little impact on plant health.  There are also natural enemies that help keep fall webworms in check and prevent serious outbreaks.  

If you want to try to improve the tree's appearance, you can try to pull the webbing and caterpillars off the branches (assuming you can reach them).  Although it may be difficult to remove the entire web, you may be able to damage it enough to eliminate the fall webworms.  You can prune out branches containing webs as along as removal is not excessive or the tree or shrub is left unsightly. Do not attempt to burn webs; this is more harmful to the tree than any control that is achieved.

If there are circumstances where it is necessary to treat fall webworms, they are vulnerable to insecticides if they are applied soon after the caterpillars start to construct their webs.  There are a variety of residual products that can be effective, including permethrin and bifenthrin.  If you wish to use a low impact product, try Bacillus thuringiensis, a bacterial insecticide.  It is specific to butterfly and moth caterpillars and has no impact on other insects as well as people and animals.  Once webs are larger, direct sprays do not penetrate through the webbing very well.  Another option is to use the dinotefuran, a type of systemic insecticide.  Another, systemic insecticide,  imidacloprid, however, is not very effective against caterpillars. 

Emerald Ash Borer Found in Two New Sites

Jeffrey Hahn, Asst. Extension Entomologist

Jeff Hahn

Photo 1: EAB on purple trap

Emerald ash borer (EAB) has been confirmed in two new locations by the Minnesota Dept. of Agriculture (MDA) on Friday August 26. One find was detected in the city of La Crescent in Houston county while the second was found in the Great River Bluffs State Park in Winona county, just eight miles apart. This is the first time EAB has been found in Winona county. Both discoveries were made when an EAB adult was found on sticky purple panel traps that were deployed by the MDA. No infested trees have been found to date, although surveys in those areas are ongoing.

For more information see the MDA news release

Late Breaking News:  On Wednesday August 31, MDA reported that EAB was found on another purple trap about 7 miles northwest of the positive trap location at Great River Bluffs State Park and about 7 miles east of Winona. 

Giant Swallowtails

Jeffrey Hahn, Asst. Extension Entomologist

Wendy Pritchard

Photo 1: It's a treat to see a giant swallowtail

There have been several reports of people seeing giant swallowtails, Papilio cresphontes, in the Twin Cities areas recently (they undoubtedly have been seen in other areas of Minnesota as well). This is noteworthy as these spectacular butterflies are not native to Minnesota but can occasionally be found during the summer as migrants from the south.

You can recognize a giant swallowtail because of its size, its wingspan ranges from 4" - 5 ½", and its black wings with yellow spots; the yellow spots on the forewings form an 'x'. Don't confuse it with a black swallowtail which also has black wings but is smaller, its wingspan is as large as 3 ½" and the yellow spots on its forewings are parallel and do not cross. Giant swallowtails can not reproduce in Minnesota as they need citrus trees and related plants for food for the larvae.

Be Aware of Wasps

Jeffrey Hahn, Asst. Extension Entomologist

Jeff Hahn

Photo 1: Aerial yellowjacket nest

This is a common time of the year for wasp (primarily yellowjacket) nests to become conspicuous and more noticeable by homeowners. These nests have been present all summer but were small enough that they were not noticed then. Although this year would be considered to be no more than an average year for wasps primarily due to the late spring we experienced, if you have a wasp nest present on your property they are still a potential problem. What you decide to do with a nest can depend on a number of factors, such as how close to human traffic the nest is, is the nest is exposed or not, and how close to a hard frost we are.

For more information, see the following article on wasps (yellowjackets),

Japanese Beetle (JB) Q & A

Jeffrey Hahn, Asst. Extension Entomologist

Q. Where did JB come from?

A. The first JB was found in Minnesota in 1968 after which the Minnesota Dept. of Agriculture (MDA) started a trapping program. Despite traps being set up in the Twin Cites area, between 1969 - 1979, only three beetles were captured. Between 1980 - 1983, only 16 JB were found. There were no trapping between 1984 - 1991.

Jeff Hahn

Photo 1: Japanese beetle adult close-up. Note feeding damage.

The trapping program resumed in 1991 and in 1992 298 JB were trapped. In 1994, over 6,800 were trapped in 12 counties. In1999, nearly 36,000 were trapped; over a half million in 2000; and over 1 million JB trapped in 15 counties in 2001 (99% of these were found in Hennepin and Washington counties). Then in 2002, the numbers crashed and only 1,682 in 19 counties were found.

MDA discontinued their trapping program after that, feeling that JB was established. Very few reports were received by Extension over the next several years. Starting in 2005, Extension started receiving noticeably more calls and e-mails on JB. Each year afterwards contacts about JB gradually increased and as they become more common each year. As of 2009, JB had been found in 27 counties, primarily in the Twin Cites and the southeast and south central regions of the state.

Q. How long do they feed?

A. JB emerge about July 1 each year and are active through September. They have been reported as late as October during late falls.

Jeff Hahn

Photo 2: Physically remove Japanese beetles and toss them into a pail of soapy water.

Q. Are there any non-chemical methods for managing JB?

A. The best method is physical removal. A good way to do this is to take a pail of soapy water and brush them off or pick them off by hand so they end up in the pail. The soapy water kills them. If you just knock them off plants, they will fly and return to them. It is best to do this right away in the morning or in evening when they are less active.

Q. Are there any low impact products I can use on JB?

A. There are a couple you could consider. Products containing Neem are reasonably effective, especially when JB numbers are low to moderate. They act as an antifeedant to deter JB from feeding on plants. Pyrethrins containing PBO (Piperonyl butoxide) is also effective. Both products need to be reapplied fairly frequently.

Q. What residual insecticides can I use to treat JB?

A. Neonicotinoid insecticides, especially imidacloprid (various trade names) and dinotefuran (Safari) are good choices. They are systemic, are easy to apply, and are long lasting. They do not kill JB quickly but they do cause them to stop feeding with death coming later. One important drawback of these products is they are very toxic to bees. Avoid treating trees and shrubs, like linden and roses, that are attractive to bees. It doesn't matter that the trees and shrubs are not flowering at the time of application as these insecticides will be active for a year.  Another consideration is that it takes some time, especially for imidacloprid, for the tree to take up the insecticide.  You need to factor this lag time when using these products.

There are also a variety of residual insecticides that you spray directly onto the leaves that are effective, including pyrethroids like permethrin, bifenthrin, esvenfalerate, and lambda cyhalathron, and carbaryl. Be sure that the foliage is throughly treated.

Jeff Hahn

Photo 3: Japanese beetle damage on linden.

Trees and shrubs are best treated as soon as damage and JB are first noticed. Since they have had about a month to feed, you should consider how much damage has already occurred if you are still thinking of treating. If over half of the tree or shrub has been defoliated then it probably not worthwhile to treat it any more this year. If at least half of the tree or shrub is green, then there is still value to use insecticides to help protect trees.

Q. What can I spray on food plants, like apples and raspberries.

A. There is not a simple answer to this as one active ingredient, such as permethrin, may be labeled for food plants on one product but may not be on another. People need to check to see if the particular food crop you intend to treat is on the label of the specific product you want to use. If it is, then you can use that insecticide to spray your desired edible plant. Then be sure to observe the interval between when you spray and when crops can be harvested.

If the crop you want to treat is not on the label, then don't spray it. Check the label before you buy a product and again before using it to be sure you know what plants can be treated.

Q. How effective are JB traps?

A. JB traps can catch what appears to be an impressive number of JB. However, research shows that they actually draw more JB into the area than what they catch. The result is you not only do not reduce JB adults and their damage but you actually increase the amount feeding damage that occurs to susceptible plants.

Q. How effective is it to treat my turf to prevent JB adults from getting into my garden?

A. Treating for JB grubs does not protect your yard from adult beetles. Adults are very mobile and can easily fly in from outside your property. Only treat your lawn if you are seeing damage from the grubs.

Click here for more information on Japanese Beetles.

Flowers - Beautiful, Nutritious, & Dangerous

Karl Foord

Photo 1: Goldenrod Spider "Flower Spider" "Red-spotted Crab Spider Misumena vatia; Male on top of female who has Spring azure Blue Butterfly Celastrina sp. in grasp

Karl Foord, UMN Extension Educator

While photographing lilies for the article "Lilies - One of the Queens of the Garden," I came upon a blue butterfly (perhaps a Spring Azure Celastrina sp.). I was hoping to photograph it when it had opened its wings. I slowly drew closer only to realize that it was not to open its wings again. It was in the grasp of a flower spider (perhaps a Goldenrod Spider or "Red-spotted Crab Spider" Misumena vatia).

A smaller spider perhaps a male of the species jumped on top of the other spider and then fled. I would expect this was a wise thing to do. This spider was particularly well camouflaged on this Lilium 'Heart's Desire' Asiatic Lily. Flowers are beautiful, nutritious and dangerous, depending on your point of view.

Karl Foord

Asian Long-horned Beetle Found in Ohio

Jeffrey Hahn, Asst. Extension Entomologist

Kenneth R. Law, USDA APHIS PPQ

Asian long-horned beetle adult.

The Asian longhorned beetle (ALB), Anoplophora glabripennis, was recently found for the first time in Ohio, 30 miles southeast of Cincinnati. This exotic borer, originally from Asia from southern China, Korea, and Japan, was first found in North America in 1996 in New York. Two years later it was found in Chicago (but was eradicated there). Since then, it has also been discovered in New Jersey (2002), Toronto (2003), and Massachusetts (2008) before being found in Ohio.

This is a good reminder to be watching for ALB in Minnesota. Although it has not been discovered here yet, we have a lot of trees this borer loves to attack, including maple, American elm, and willow. It is important for people to be familiar with ALB so suspicious insects can be reported. In Ohio, a private citizen found insects in three maples that she thought could be ALB and reported it to entomologist at Ohio State University who then passed this on to USDA-APHIS for verification.

Steven Katovich, USDA Forest Service

Asian long-horned beetle larva.

The best way to recognize ALB is from the adults. They are large insects, ranging in size from 1 - 1 ½ inches long (not counting the antennae). Like other long-horned beetles, ALB has antennae that as long or longer than its body, up to four inches in length. ALB particularly has distinctive black and white banded antennae. It's body is a glossy black with as many as 20 white distinct spots on it. Because of this, ALB is sometimes called the starry sky beetle. Adults are active throughout the summer and into the fall.

Don't confuse ALB with the whitespotted sawyer, a native long-horned borer in Minnesota. A whitespotted sawyer is about 3/4 - 1 1/4 inches long and has a dull black body with indistinct white spots or patches. Males lack any banding on their antennae while females possess only faint bands. Whitespotted sawyers are associated with conifers.

Dennis Haugen, USDA Forest Service

Asian long-horned beetle exit hole.

You may see ALB larvae in wood. They are legless and cylindrical in shape with a head that just sticks out of the body. They are large, growing up to two inches in size. These larvae create oval tunnels as they bore into the sapwood and heartwood. Although it is easy to identify ALB as a type of roundheaded borer (the larvae of long-horned beetle), it is difficult to identify roundheaded borers as ALB.

If you have maple, elm, or willow in your yard or other hardwoods like birch and poplar, watch for signs of infested trees. Because ALB is such a large insect, when it emerges as an adult, it creates a large, 3/8 - 3/4 inch wide round exit hole in the trunk or branches. This large enough to stick the eraser end of a pencil into the hole. Other potential signs of ALB include sawdust on the ground or the fork of branches, sap oozing from the exit holes, and the presence of small oval to round shallow pits chewed into the trunk or branches - the females chew these for a place to lay eggs.

If you think you have found ALB, contact the Minnesota Department of Agriculture's "Arrest the Pest" Hotline at 651-201-6684 (Metro Area) or 1-888-545-6684 (Greater Minnesota).

Watch For Earwigs in Your Garden

Jeff Hahn

Immature earwigs on milkweed.

Jeffrey Hahn, Asst. Extension Entomologist

Immature earwigs were have been seen in gardens recently and will soon turn into adults. Many areas of Minnesota experienced high earwig numbers last year. Be on the watch for them in your garden this summer. Earwigs are about 5/8 inch long, with a flat, reddish brown body and very short wings. They look like a cockroach or a rove beetle but are distinctive because of the pair of pinchers (cerci) on the tip of their abdomen. Nymphs are similar to adults except they are smaller and generally lighter in color.

Earwigs are most active at night and like to hide during the day in dark, tight, damp areas, like under potted plants, cracks between bricks and pavers, and on plants in buds and folded leaves. Earwigs are scavengers, feeding on damaged and decaying plant matter as well as weakened or dead insects and other small organisms. Earwigs can also feed on healthy plant material. This is when they can become a problem in gardens.

Earwigs can damage flowers, like dahlias and marigolds, chewing irregular holes in flower blossoms and in leaves. They are also reported to attack various vegetables, corn silk, and seedlings. Some of this damage can be confused with slug feeding. However, slugs leave a slime trail while earwigs do not. If you are not sure what is causing the damage you are finding, go outside at night with a flashlight check under plants for earwigs and other pests.

Dave Moen

Earwig damage on dahlias.

To reduce the number of earwigs around your garden, clean up debris that earwigs can hide under, such as leaves, plant debris, bricks, piles of lumber, and similar things. It can also be useful to thin out or remove mulch. You can also set out rolled up newspapers to trap earwigs. Put them into your landscape or garden during evening. In the morning shake the traps above a pail of soapy water to remove the earwigs.

Minimize excess moisture in the landscape. Be sure that the landscape has good drainage and that irrigation systems are working properly. A good strategy when watering is to irrigate more thoroughly and deeply but less often so the surface of the soil remains drier.

You can also protect plants with an insecticide application. An effective method is to treat the surrounding mulch where the earwigs are hiding. Use a drench, e.g. lambda cyhalothrin or carbaryl for this. You may need to attach the product to a hose to get sufficient volume. You may also be able to protect individual plants by applying a spray, e..g. permethrin, deltamethrin, or acetamiprid or a dust, e.g. permethrin or deltamethrin, to plants when damage is first noticed.

All Hail to the (Ant) Queen

Jeffrey Hahn, Asst. Extension Entomologist

Jeff Hahn

Photo 1: Pavement ant queens (note two-segmented petiole between thorax and abdomen).

There have been questions lately about winged ants being found in and around homes and other buildings. Nearly all ant species in Minnesota (Pharaoh ants are an exception to this) produce mating swarms, i.e. winged males and females, at certain times of the year. These reproductives emerge and fly out of the nest, typically in large numbers. The males die shortly after mating with queens. The queens fly off in search for a suitable place to start a nest, although the vast majority do not survive long, being eaten or succumbing to the elements.

Upon landing, the queen breaks off their wings. As she starts construction of the nest, she lays a batch of eggs which she cares for until they mature into adults. From that point on, the workers assume all of the work responsibilities and the queen's sole job is to lay eggs. She is taken care of by worker ants and remains in the nest her entire life.

Jeff Hahn

Photo 2: Carpenter ant queen (note one-segmented petiole between thorax and abdomen).

In Minnesota, there are two common ants that people see swarming in the spring, carpenter ants and pavement ants. Carpenter ant queens are typically black and large, about ½ inch long, although some species are smaller and can vary in color. However all carpenter ants have a one segmented node between the thorax and abdomen. Pavement ant queens are about 1/4 - 3/8 inch long, brownish and has a two-segmented node.

Finding a swarm of ants indicates a nest is nearby. However, a swarm, in and of itself, is not necessarily a problem. For the most part, like when they are found in your yard, they are not anything more than a nuisance. Under these circumstances, just ignore them until they go away on their own.

If winged ants are found indoors, then there is a nest inside the home. Correctly identifying the ant species will help determine the best control. Pavement ants nest in the soil under objects, like sidewalks, driveways, stones, and concrete slab construction of homes. When found inside, they are annoying but are not a structural problem. The only necessary control when pavement ant swarmers are inside is to physically remove them, especially if you only see winged ants and not any workers

Finding winged carpenter ants indoors is another matter. They nest in water damaged wood and can potentially damage buildings. You can be somewhat patient when trying to determine where they are coming from and attempting control but you should not ignore them indefinitely. Their elimination is best done by a professional pest management company.

However, sometimes a wingless carpenter ant queen is found walking around in or around a home. Because it is a carpenter ant, people are concerned about a nest being in the home. But remember that this queen has not established a nest yet and is still looking for a place to begin one. Her presence does not mean a colony is in the home. The only necessary control is to dispatch her.

Tent Caterpillars

Jeffrey Hahn, Asst. Extension Entomologist

Michelle Grabowski

Small eastern tent caterpillar tent.

There are two common species of tent caterpillars that are now active in Minnesota, eastern tent caterpillars and forest tent caterpillars. Both normally hatch closer to early May, but the cool spring weather we have experienced has slowed down their emergence and they only first started to appear closer to the middle of the month. Here is how you can distinguish between these insects.

Eastern Tent Caterpillars

This insect is easy to identify because it constructs silken webs in the fork of branches as soon as they young larvae hatch. The caterpillars feed outside of the tents on leaves during the day (as long as the weather is nice) and return to the webbing at the end of the day and during rainy weather for protection.

The caterpillars are bluish black with yellow and a white stripe running the length of the top of its body. They are also mostly smooth except for a series of hairs sticking out along the side of their bodies. They are two inches when fully grown.

Look for eastern tent caterpillars on hardwood trees, particularly fruit trees, like apple, chokecherry, crabapple, plum, and cherry. Eastern tent caterpillars are common most springs. They maintain relatively steady populations from year to year and generally do not occur in outbreak numbers.

Forest tent caterpillars

Also known as armyworms, forest tent caterpillars are familiar insects in the north and central areas of Minnesota. These caterpillars are blue and black with distinctive footprint or keyhole shaped white spots on their backs. They are mostly smooth except for hairs that stick out along the sides of their body. They grow to be two inches long when fully grown. Despite their name, they do not make conspicuous webs on trees.

Jeff Hahn

Several day old forest tent caterpillars on oak.

Forest tent caterpillars feed on many deciduous trees, including aspen, birch, maple, crabapple, apple, ash, oak, and elm. They go through cycles of tremendously large numbers, lasting 5 to 8 years, before collapsing to such low numbers that they are not noticed. Periods of low populations lasts about 8 to 13 years. Forest tent caterpillars peaked in 2002 and their numbers have since crashed.

The Minnesota Department of Natural Resources (DNR) reports that in 2010 just over 70,000 acres were defoliated, primarily in the middle one-third of Minnesota in a crescent that extends from south of Mille Lacs Lake through St. Cloud to Wilmar and up through Detroit Lakes. There were also a few isolated areas of defoliation in Hubbard, Cass and Crow Wing Counties. Forest tent caterpillars are also found in the Twin Cities area. Their numbers are expected to increase some in 2011 compared to last year but an outbreak is not expected.


The decision to treat tent caterpillars should be made based on several criteria. First, consider what percentage of leaves have been eaten. If only a few branches are affected, the tree can tolerate that damage. Leaf feeding tends to be more a cosmetic problem and not one that threatens the health of the tree. Even if defoliation is severe, healthy, well-established trees can withstand this feeding in a given year. However, young trees are less tolerant and should be protected. Unhealthy, stressed trees should also be protected from severe defoliation.

Another important consideration is the size of the insect. Ideally these insects should be treated when they are 1/2 their full-grown size or smaller, i.e. about one inch in size. The larger they are, the closer they are to being done feeding. Because the tent caterpillars emerged later than usual, they are not as far as long as they would normally be by the beginning of June. There is still time to treat them and minimize their defoliation. However, if by the time you see them, the are close to two inches long, it is not worth treating them.

There are a variety of residual insecticides that you can use if it is desirable to protect your trees. Consider using products that have a low impact on the environment, such as Bacillus thuringiensis, spinosad, and insecticidal soap. Bacillus thuringiensis is a particularly good product if the tree is flowering since it will not harm visiting honey bees.


Photo 1, Karl Foord.

Karl Foord, UMN Extension Educator

Keep an eye out for tent caterpillars and Pine sawfly larvae. Look for shriveled and missing needles on pine branches just below the newly forming candles (Photo 1). The larvae are gregarious and form in numbers on these sections of the plant. They are quite voracious and can strip a tree quickly (Photo 2). It is best to wash them off the plant with water rather than to use an insecticide. See Jeff Hahn's article for a more detailed account of pine sawfly.

Pine sawfly larvae exhibit some fascinating forms of defensive behavior. Colonies of larvae will rear their heads in unison when disturbed. This behavior may serve to startle potential predators (

Pine sawfly larvae also collect pine resin in a special gut compartment as they feed. Whenkf461-1.jpg

Photo 2, Karl Foord.

attacked by a predator, the larva will regurgitate a droplet of pine resin and try to dab it on the predator. Ants and other predatory insects will often abort the attack and try to remove the sticky resin by cleaning behavior.

Solitary Bees With a Twist

Jeffrey Hahn, Asst. Extension Entomologist

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Photo 1: Andrenid bee. Jeff Hahn.

Andrenid bees, especially Andrena spp., are common insects that are sometimes seen in yards and gardens in spring. They are small to medium sized insects, about 1/4 - ½ inch long. They are hairy, dark-colored insects, often with a thick mat of yellow hairs on their thorax.

They typically overwinter as pupae and emerge as adults as soon as the weather becomes warm, living for about a month. Andrenid bees nest in the ground, preferring sunny, dry sites with sparse grass or few plants. They create cylindrical tunnels where they spend essentially their entire life preparing these nests for their young. They provision them with pollen balls on which the larvae feed during summer.

Unlike honey bees and bumble bees, which are social insects living in colonies, andrenid bees are solitary insects that live by themselves. They are responsible for all of the work that is required to maintain the nest and provide for the larvae. However, andrenid bees typically live gregariously, i.e. many individual nests in a small area despite the appearance that they are coming from a single nest. Copy of P5180167.JPG

Photo 2: Andrenid bee nests (notice how many there are in this small area). Jeff Hahn.

Fortunately, andrenid bees are gentle and stings are extremely rare. It is possible they might sting if they are mishandled. However, there are many reports of people in close proximity to these bees without being stung.

When dealing with andrenid bees, tolerate them as much as possible. Bees are beneficial because they are pollinators and should be preserved whenever possible. Remember that they are gentle with little risk of stings. They are also only active for about a month and they shouldn't be around much longer this spring. Insecticides are a possibility but should only be used as a last resort.

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Photo 3: Cuckoo bee, Nomada sp., entering an andrenid bee nest. Jeff Hahn.

There is a plot twist in one particular andrenid bee site that was observed recently. Another insect was apparently nesting in the ground in same area as the andrenid bees. They were reddish brown with a yellow striped abdomen, few hairs on their bodies, and were a little smaller. After collecting and examining a specimen, they were identified as cuckoo bees, Nomada sp. Cuckoo bees are wasp-like in appearance and are not pollinators like most bees. Instead they are parasitic on other bees, entering and laying their eggs into the host bee's nests so the food gathered will feed the cuckoo bees' young. The world of entomology never ceases to amaze.

EAB Awareness Week

Jeffrey Hahn, Asst. Extension Entomologist

With a stroke of his pen, Governor Mark Dayton signed a proclamation officially declaring May 22 - 28 as EAB (Emerald Ash Borer) Week in Minnesota. This is a good opportunity to remind people that EAB is still a serious pest that threatens our state's nearly 1 billion ash trees. That week also corresponds with the official start to camping season as people travel for the Memorial Day weekend.

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Photo 1: Adult emerald ash borer. Jeff Hahn.

The theme for EAB Awareness Week is 'Keep our trees safe. Use MDA (Minnesota Department of Agriculture) certified or local firewood.' This is such a critical message for people to understand that the one of the most important methods for EAB to be transported into areas that are uninfested is through firewood. That is why people are strongly encouraged to leave their firewood at home and buy from local, approved firewood vendors.

Currently EAB is known only in Ramsey, Hennepin, and Houston counties. MDA has enacted quarantines in these counties to try to prevent infested ash product from moving out of these areas and into uninfested sites. To supplement this effort, MDA also continues to conduct surveys using purple traps to try to detect EAB soon after it enters an area. They have also enacted management strategies to slow the rate of spread of EAB

Citizens can also help by reporting insects they suspect are EAB and potentially EAB infested ash trees. If you think you have discovered EAB go to this step by step guide. If you can still can not rule this invasive pest out by the end of the page, then contact the University of Minnesota Forest Resources Extension who will put you in contact with someone that can help you determine whether you have EAB.

For more information on EAB, see the University of Minnesota Extension EAB web site.

Protect Yourself From Tick Diseases

Jeffrey Hahn, Asst. Extension Entomologist

The Minnesota Department of Health (MDH) recently issued a news release detailing the marked increase in the number of tick-borne diseases in 2010. MDH tallied 2,069 cases of Lyme disease, Human anaplasmosis and babesiosis from last year. While the number of Lyme disease cases only went up a little, Human anaplasmosis cases more than doubled and instances of babesiosis were nearly twice as much compared to 2009.

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Photo 1: Adult female blacklegged tick. Jeff Hahn.

Blacklegged ticks (formerly known as deer ticks) is the species responsible for transmitting these diseases. The highest risk areas in Minnesota are in the eastern, central, and southeast areas of the state. Symptoms are variable. When dealing with Lyme disease, many cases (but not all) exhibit a red, circular, bull's-eye rash. Other disease symptoms can range from no reaction to arthritis, neuropathy, headaches, fevers, chills, and muscle aches, joint swelling, cardiac and nervous system problems, and, in a few cases, death. For more information on tick-borne disease, see the Unversity of Minnesota Extension fact sheet, Tick-Borne Diseases in Minnesota.

The risk of disease can occur any time from spring through fall. Take the proper precautions to protect yourselves from ticks.

- Avoid areas where ticks are likely to be found. Particularly stay on trails and avoid walking through woody, brushy, or grassy areas where ticks are most common.

- Wear protective clothing, such as long-sleeved shirts and long pants. Wear light colored clothes so it is easier to see ticks on you. For added protection, tuck pants inside socks.

- Use repellents for additional protection. Apply them to socks, pant legs, and parts of clothing that may brush against vegetation. DEET and permethrin are effective. Apply DEET to clothing and skin but apply permethrin only to clothing.

- Be sure to check your clothes and yourself when you have been outdoors in known tick areas. Save any suspected blacklegged ticks for identification.

When dealing with ticks in your yard, do the following:

- Keep grass and vegetation short around homes, where it borders lawns, along paths, and in areas where people may contact ticks as ticks are less likely to survive in short grass.

-. Remove leaf litter and brush, especially in areas where the lawn borders grassy, brushy areas. Also prune trees and shrubs in these areas to allow more sunlight through as ticks are more common in shaded areas.

- When large numbers of ticks are present in areas adjacent to home yards, you can treat the edges of wooded or brushy areas and paths to help reduce tick numbers. Use an insecticide labeled for a turf area, such as those containing permethrin, cyfluthrin, or carbaryl. Do not spray such an area more than once a year.

- It is not necessary to treat your lawn for ticks as ticks rarely infest maintained yards.

For more information on Minnesota Ticks, see the University of Minnesota Extension fact sheet, Ticks and Their Control.

What Is That Insect?

Jeffrey Hahn, Asst. Extension Entomologist

An interesting insect, found under unusual circumstances, was reported recently. A gentleman had a large dead branch pruned out of his maple in February. It had rotted in the center and was a hazard that needed to be removed. He cut the limb into smaller pieces and stacked them in April. He noticed in one branch section where the wood had rotted an accumulation of mud.

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Photo 1: Rat-tailed maggots. Kyle Jensen.

He removed the mud and uncovered several pinkish larvae with long 'tails'. They were legless with no obvious head. These insect larvae are rat-tailed maggots, Eristalis spp. The most commonly encountered species is Eristalis tenax. The body of a mature rat-tailed maggot is about 3/4 inch long with the telescopic breathing tube (the 'tail') as long as two inches. This insect belongs to the family Syrphidae which are commonly called flower flies or hover flies because adults are typically found around flowers and are able to hover in place when flying.

Rat-tailed maggots typically live in stagnant, low oxygenated water with high levels of organic matter. They have been found in sewage water, manure pits, and other types of polluted water as well as ponds with a lot of algae. They are also commonly found in rotting, decaying organic matter, including animal carcasses, damp compost, and wet, decaying leaves.

They are essentially harmless to people, although there have been some reported cases where they are involved in myiasis, i.e. infesting living tissue of people and animals. Rat-tailed maggots in particular would infest gastrointestinal tissue. Fortunately, this would be considered extremely rare and unusual in Minnesota.

There is not a good explanation for why these rat-tailed maggots were found in the rotting limb of a tree. There is a precedent for rat-tailed maggots being associated with moist, decaying plant matter so it is somewhat conceivable for them to be found in rotting wood. But for them to spend their lifetime in the rotting center of a tree limb still attached would be considered unusual at best.

Wasp Nests and Wasps in Spring

Jeffrey Hahn, Asst. UMN Extension Entomologist

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Photo 1: Don't worry about wasps in this nest in early spring. Jeff Hahn.

As our attention finally turns to spring, there could be some loose ends to tie up from last fall. For people that experienced wasp nests in their home, they may be wondering what they should do with any wasps that may remain in them. Fortunately, there are no longer any wasps alive in those nests.

Late last summer, new queens were produced. After mating, they left the nest, and flew off to eventually find sheltered sites in which to overwinter. Meanwhile back at the nest, the old queen and workers continued with their daily routines until freezing weather killed them. Newly mated queens do not return to their old nests but instead will construct their own nests when spring begins.

So what does that mean for nests in and around your home this spring. You can largely ignore them. One exception to this would be if you experienced a wasp nest in a wall void or somewhere within the structure of your home, such that you could not see the nest but you can see wasps flying back and forth from an opening. In this case, you should seal up those openings. The reason is that while the old nest is not reused, a new nest could be built in the same space. Early spring is a good time to seal those openings before wasp queens are active and begin building new nests.


Photo 2: Paper wasps overwinter gregariously. Jeff Hahn.

There are have also been reports of wasps indoors during mild late winter days. There has been concern that there is a wasp nest in the home and the warm temperatures are 'waking' them up. While most wasp queens will overwinter on their own, paper wasp (Polistes spp.) queens seek shelter gregariously, i.e. in nonsocial groups. It is not uncommon to see a dozen or more paper wasps but fortunately, this is not an indication of a nest. If you encounter this situation, just open the window and let them fly out or take a fly swatter or rolled up newspaper and dispatch them.

Webbing Clothes Moths

Jeffrey Hahn, Asst. UMN Extension Entomologist

The most common small moths found indoors, e.g. Indianmeal moths, are usually associatedCopy of DSC_0152.JPG

Photo 1: Webbing clothes moth adult Jeff Hahn.

with stored foods. However, occasionally you may encounter small moths that attack fabric. The most common species is the webbing clothes moth. The adult webbing clothes moth has buff colored wings with no spots or markings on them. The wings are folded behind their back when at rest and the insect measures about 1/4 to 1/3 inches long. Particularly characteristic is the mop of reddish brown hairs on its head. Webbing cloth moth adults avoid light and generally seek out dark areas of rooms.

The larvae are whitish with dark colored heads and are no larger than ½ inch long. They feed on wool, fur, feathers hair, and other materials of animal origin. They are not interested in plant material, like cotton and generally do not attack synthetic material unless it is blended with wool or is stained, e.g. with sweat or food. Webbing clothes moth larvae graze on the surface of the material, creating irregular holes in the fabric. They also create silken tubes or mats on the fabric as they feed which helps to identify the damage.

Prevention is the best control to avoid webbing clothes moths. You can do this through regular vacuuming including carpets and rugs, along baseboards, under furniture and in closets as well as removing scraps and remnants of wool, fur, and similar materials. Regularly inspect susceptible clothes, like wool sweaters and suits, wool rugs, animal mounts, and other material for signs of infestation; the sooner an infestation is discovered, the sooner it can be controlled.

When putting susceptible clothes away for the summer be sure they are dry cleaned orWebbingClothesMoth.jpg

Photo 2: Webbing clothes moth damage, adult and larva. Clemson-USDA.

laundered. It best to place them in airtight containers, such as a plastic sweater box. Wood chests can also work if the top fits tightly. For added protection, you can place mothballs or crystals (naphthalene) with the clothes in the storage containers. However, keep in mind the smell of naphthalene may be challenging to remove from clothing. Dry clean clothing again before wearing to help remove any odor. Remember that naphthalene is not a repellant but instead uses a concentration of vapors to kill insects. Placing moth balls or crystals loose in a closet or similar areas will not prevent webbing clothes moths. Cedar chips, although popular as an insect repellent, do not effectively deter webbing clothes moths.

If you find an infestation of webbing clothes moths, either remove and throw away the source of the infestation or have it laundered or dry cleaned. Be sure to vacuum or other wise clean up the immediate area to remove any potential additional sources of infestation. Severe webbing clothes moth infestations may require the service of a pest management service.

Where Did Those Annoying Insects Come From?

Thumbnail image for boxelder bug Jeff Hahn.jpg

Jeffrey Hahn, Asst. UMN Extension Entomologist

Photo 1: Boxelder bug. Jeff Hahn .

It is common during mild winter weather to see various nuisance insects in your home, especially boxelder bugs, multicolored Asian lady beetles, and western conifer seed bugs. Despite the appearance that they have laid eggs and are hatching now, these insects have actually been in homes since fall when they first entered structures.

When they came into buildings in the fall, some insects accidentally moved all the way into homes. Others took refuge in wall voids, attics, and other nooks and crannies. As long as these areas stayed cold, they remained inactive. However, when it became warm, they 'woke up' and moved towards warmth which would be the inside of your home. As we get closer to spring, we see this occurring more frequently. These insects often congregate together in clusters in these harborages so as these areas warm up, not all of the insects become active at the same time. Or they just could occur in places in the home that warm up at different times. The end result is that there will be insects emerging up at different times during the winter.

When you see these insects now, your options are limited. Your best bet is to physically remove them, e.g. with a vacuum. Insecticides are generally not suggested as it will not prevent the insects from emerging and you have to physically remove them whether they are dead or alive. If this is a problem you deal with every year, be sure to target control in the fall before the insects start moving inside. The best tactics are sealing as many obvious spaces that you can find and supplementing that with an insecticide treatment. Once these insects are in your home, there is little you can do.

New Publication on EAB Insecticides Now Available

Jeffrey Hahn, Asst. UMN Extension Entomologisteab fs

Photo 1: Check out this new EAB fact sheet. Jeff Hahn .

A four page fact sheet entitled Frequently Asked Questions Regarding Potential Side Effects of Systemic Insecticides Used To Control Emerald Ash Borer was recently completed.  This publication was written by entomologists at the University of Ohio State, Michigan State University and University of Minnesota Extension and reviewed by 14 specialists.  It was produced to help answer common questions people have about the insecticides used to treat emerald ash borer using the most current research based information.  As emerald ash borer becomes more widespread in Minnesota (and other areas of the country) and insecticides are considered, more people will have these questions and need access to unbiased, fact-based information.  You can find this publication at the following link

Mosquitoes Out of Season

Jeffrey Hahn, Asst. UMN Extension Entomologist

When living in Minnesota, we know that mosquitoes are a fact of life. However, we at leastThumbnail image for Anopheles punctipennis - bunni olson.jpg

Photo 1: Anopheles punctipennis. Bunni Olson.

can take consolation that this is a problem during the summer and not something we need to deal with in the dead of winter. And yet, a homeowner e-mailed that she was finding odd insects in her home that she said looked just like mosquitoes. She sent an image that showed what looked like a mosquito but with banded wings. Mosquitoes typically do not have banded wings but there are some closely related insect groups, like crane flies, that commonly do.

However, the long proboscis (mouthparts) and scales on its wings give the insect away as a mosquito. You can identify it as female because its antennae with few hairs on it and is not feather-like as a male would be. You can even identify the mosquito as an Anopheles sp. from the long palps adjacent to the proboscis. The wings have alternating black and light colored patches on their wings which are distinctive and diagnostic for the species Anopheles punctipennis (no common name).

Anopheles punctipennis, like other Anopheles species, spends winters in Minnesota in a diapause, a period of inactivity somewhat similar to hibernation. In fall, this species seeks dark, quiet, protected areas and commonly are found in abandoned buildings, hollow trees, caves, garages, and basements where they would normally stay for the winter. For individuals overwintering indoors, it is possible for some movement by a person or pet near to where they are resting to cause them to become active. Fortunately, Anopheles punctipennis is not known to transmit any disease and in fact are very unlikely to even bite now. They are just a nuisance and you do not need to take any special control measures against them.

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