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EAB is confirmed in Dakota County

Jeffrey Hahn, Extension Entomologist

(The following information is taken from a December 23, 2014 newsletter from the Minnesota Department of Agriculture)

Jeff Hahn, Univ. of MN Extension

Photo 1: Ash trees marked for removal due to EAB.

The Minnesota Department of Agriculture (MDA) confirmed an emerald ash borer (EAB) infestation in Dakota County. EAB was found in an ash tree in Lebanon Hills Regional Park in the city of Eagan, just north of the border with Apple Valley. The infested tree was detected through a routine visual survey of ash trees currently being conducted by the MDA. This survey is designed to find EAB in counties bordering the Ramsey and Hennepin County quarantine area.

Dakota County becomes the sixth county in Minnesota to confirm EAB. Additionally, EAB has also been found in Hennepin, Ramsey, Houston, Winona, and Olmsted (which was just confirmed this August) counties. These counties all have a state and federal quarantine established. The quarantine is in place to help prevent EAB from spreading outside a known infested area. It is designed to limit the movement of any items that may be infested with EAB, including ash trees and ash tree limbs, as well as all hardwood firewood.

This is especially important for Minnesota as there are approximately one billion ash trees present in this state. And all are susceptible to this invasive beetle. It is critical that people be aware of and follow the quarantine to minimize the spread of EAB. The biggest risk of spreading EAB comes from people unknowingly moving firewood or other ash products harboring larvae.

Every Minnesotan can help prevent EAB from spreading by taking the following steps:

• Don't transport firewood. Buy firewood locally from approved vendors, and burn it where you buy it;

• Be aware of the quarantine restrictions. If you live in a quarantined county, be aware of the restrictions on movement of products such as ash trees, wood chips, and firewood. Details can be found online at; and,

• If you think you have seen an infested ash tree, go to and use the "Do I Have Emerald Ash Borer?" checklist or contact MDA's Arrest the Pest Hotline by calling 888-545-6684 or emailing to report your concerns.

For more information about EAB, see the University of Minnesota Extension publication, Emerald ash borer in Minnesota.

The original MDA news release can be found here.   

Spotted lanternfly is now in U.S.

Jeffrey Hahn, Extension Entomologist

A new invasive insect species from Asia, the spotted lanternfly, Lycorma delicatula, was discovered last month in Pennsylvania. Despite its name, this insect is not a true fly but is actually a type of planthopper which is related to aphids, leafhoppers, cicadas and similar insects.

Lawrence Barringer, Pennsylvania Dept of Agriculture

Photo 1: Spotted Lanternfly. Note spots on most of the wing and the lacey pattern on the wing tips.

A spotted lanternfly is a large insect, measuring about one and a half inches long. It is very distinctly colored and patterned. About 2/3 of the forewing is a light gray with small oval, black spots. The wing tips have a series of tiny rectangular black spots that give it a lacey appearance. The hind wings, when exposed, are brightly colored orange-red, black and white.

There are some native insects that could be confused with a spotted lanternfly, especially tiger moths and underwing moths which also can have red hind wings. However, moths are much better fliers compared to a spotted lanternfly. Moths also do not jump while a spotted lanternfly (and other planthoppers) are good jumpers.

The spotted lanternfly is known to attack about 65 different plant hosts in Korea, especially tree of heaven and grapes. It is also known to attack plants in the same genera as apple, willow, oak, lilac, rose, maple, poplar, and pine. Spotted lanternflies (like other planthoppers) damages plants by using its needle-like mouthparts to feed on plant sap.

It is unclear what the potential for damage would be if this insect becomes established in Minnesota. While there are many plants on which they are known to feed that are present in this state, a key to their ability to infest an area seems to hinge on the presence of tree of heaven which is not a native to Minnesota. In fact only one specimen is presently known to occur in the state. The question then is whether this insect could thrive on other plants. Time will tell.

If you find an insect that you believe is a spotted lanternfly, report it to the Minnesota Department of Agriculture on their Arrest the Pest line by calling 1-888-545-6684 (voicemail) or e-mailing them at

Click here for more information on spotted lanternflies.

Pine Wilt

USDA Forest Service

Photo 1: Scots pine killed by pine wilt

Dan Miller, MN Landscape Arboretum

Two mature Scots pines (Pinus sylvestris) at the Minnesota Landscape Arboretum started showing tan-colored needles at the end of the summer this year and by late September both trees were dead. When one of the trees was being removed, Assistant Gardener Mike Walters noticed a blue stain in the sapwood of the tree and from his previous experience with a tree care company in southeastern Iowa; he suspected the tree had been killed by nematodes. Cross-sections of the blue-stained wood were soaked in water and nematodes, microscopic roundworms, could be observed with a dissecting microscope. A sample was then sent to the University of Minnesota Plant Disease Clinic and they confirmed the presence of the pine wood nematode (Bursaphelenchus xylophillus). This nematode is the primary cause of pine wilt disease.

Dan Miller, MN Landscape Arboretum

Photo 2: Cross section of a Scots pine infected with blue stain fungus

Pine wilt disease is an interesting and complex disease. Two insects, the nematodes, and a fungus are all involved. The nematodes are transmitted by the pine sawyer beetle (Monochamus spp.). The adult pine sawyers feed on the young shoots of pine trees and even though they don't cause much damage to the tree, the feeding wounds create entry points for the hitch-hiking nematodes. When the nematodes enter the tree they feed on the cells surrounding the resin ducts causing resin to leak and plug the water transport system of the tree. As the tree is weakened and becomes stressed, bark beetles are attracted. When the bark beetles bore into dying pines, blue-stain fungi living in the beetles also enters the tree. This fungus provides another food source for the nematodes so their numbers multiply even faster.

Natasha Wright

Photo 3: White spotted pine sawyer; the beetle that transmits the pine wood nematode

Pine wilt disease was first reported in Minnesota by Dr. Robert Blanchette (University of Minnesota Professor of Plant Pathology) in the early 1980s but the nematode is believed to be native to North America. Pine wilt disease occurs most commonly in stressed nonnative trees. In the Midwest, 90 percent of the trees killed by pine wilt are Scots pine. The disease occasionally appears in Austrian (Pinus nigra), mugo (Pinus mugo), and Japanese red (Pinus densiflora) as well. Native pine species are usually not susceptible. In most cases, only trees greater than 10 years old are attacked. Once the tree is attacked, it dies within a few weeks.

Y. Mamiya

Photo 4: Pine wood nematode inside the resin canal of a pine tree

At this point management options are limited. Insecticides and nematicides have not proven to be practical or effective. The best strategy is sanitation. Dead trees should be removed in the fall or early spring before the adult pine sawyers emerge and should be burned, buried, or chipped. Scots pines are not recommended for new plantings.

Millipedes in vegetables

Jeffrey Hahn, Extension Entomologist

Jerry Wenzel

Photo 1: Despite the circumstantial evidence, the millipedes did not damage this carrot; they are taking advantage of previous damage.

A couple of home gardeners encountered millipedes in some of their vegetables during October. In one case they were in a few potatoes, in another instance they were infesting a carrot. There was concern whether the millipedes were attacking healthy vegetables. Fortunately, the millipedes were not causing damage in the garden. They have weak mouthparts and are only capable of feeding on decaying organic matter. It is possible for them to feed on plants that have already been damaged but they are not attacking healthy plants.

A 2012 research article in the Journal of Applied Entomology looked at the potential of millipedes and wireworms to attack carrots (also sweet potatoes). They found the presence of the millipedes was associated with wireworm damage to carrots. The millipedes themselves were not causing damage but were there as a result of preexisting wireworm injury. That is also what is probably happening with the presence of millipedes in the potatoes. The millipedes were not damaging the tubers but were there because of other damage (probably wireworms).

Fortunately wireworm damage is not common in home gardens and this kind of injury (as well invasion by millipedes) should not be a problem very often.

Don't worry about snowfleas

Jeffrey Hahn, Extension Entomologist

Diane Peterson

Photo 1: These strange black lines are composed of large numbers of snowfleas

A couple of homeowners discovered an odd situation in their lawns during mid to late October. From a distance, they could see long, black lines in the grass. Upon closer inspection, they discovered that the black lines were actually due to many tiny insects. Examining the insects under magnification revealed that they were snowfleas, a type of springtail.

Springtails get their name because of their ability to jump. They feed on decaying organic matter as well as fungi, pollen, and algae. They are very abundant insects but because of their small size and that they are usually found in leaf litter, soil, and other generally hidden places, people do not usually notice them. Until, that is, they occur in large numbers.

Jeff Hahn, Univ. of Minnesota Extension

Photo 2: Snowfleas are most commonly seen on top of snow.

Snowfleas are particularly interesting because they are cold tolerant. They are typically seen during late winter and early spring as the snow starts to melt and they congregate, often in large numbers.  Fortunately, whether you see snowfleas now or on top of snow later, they are harmless to turf and should be ignored. They will eventually go away on their own.

Forest Pest Workshops Scheduled in SE Minnesota

Jeffrey Hahn, Extension Entomologist

Rochester will host two workshops in response to the recent discovery of emerald ash borer (EAB) in Olmsted County. The first will be a Forest Pest First Detector workshop to be held on Wednesday, November 5th from 9 AM - 3:30 PM. The cost is $40 (lunch included). In addition to EAB, other pests to be discussed include gypsy moth, Asian longhorned beetle, thousand canker disease, and Oriental bittersweet.

Jeff Hahn, Univ. of Minnesota Extension

Photo 1: Learn about emerald ash borer and other forest pests at a First Detector workshop.

The Minnesota Forest Pest First Detectors training program is designed to help identify the occurrence of Emerald Ash Borer and other forest pests in Minnesota. First Detectors are the front line of defense against likely infestations. Meeting, working with and educating the public about exotic forest pests are key activities of Forest Pest First Detectors.

Everyone is welcome to attend - even if you do not wish to become a Forest Pest First Detector! Anyone with a background in tree or forest health should consider becoming a Forest Pest First Detector.

Forest Pest First Detectors must complete online training modules before attending the one-day Forest Pest First Detector training and commit to being available and involved with the program after completing the training. Involvement includes being accessible to the public, willing to conduct site visits if necessary, report forest pest-related activities, protect confidential information, and notifying organizers of current contact information.

Visit My Minnesota Woods for more information.
To register, visit here

An Ash Management for Woodland Owners workshop is scheduled on Wednesday, November 12 from 9 AM to noon. Ash Management for Woodland Owners will include information about EAB and managing your woodland in the era of EAB. An outdoor field tour will follow an indoor presentation. This workshop is intended for woodland owners. There is a $20 fee to attend this workshop.

To register for one or both classes go to this site.

Karl Foord, Extension Educator - Horticulture

Watching these bees leave their nest and returning covered with pollen was quite enjoyable.

I will let the video speak for itself. Please enjoy. Colletes foraging.

Karl Foord, Extension Educator - Horticulture

One of our early emerging vernal native bees is in the genus Colletes. These bees are commonly called plasterer bees, cellophane, or polyester bees. This is because the bee builds an underground nest and then paints/applies/lines her nest with a cellophane-like plastic material secreted from an abdominal gland. The bee applies this material with her two-lobe tipped tongue. This secretion helps protect the developing bees from fungal disease and acts as a waterproof barrier. It is so effective that ground-nesting species can occupy areas prone to flooding.

I photographed a Colletes bee digging a nest. The nest took several hours to dig which I videoed and then cut out much of the inactivity to create a 5 minute video.

One of today's landscaping rules-of-thumb is to cover bare soil with mulch to both prevent erosion and discourage weed encroachment. This makes sense, however should we reconsider this practice in light of our need to provide nesting habitat for native bees? Perhaps there are areas in the garden or proximal to the garden which could be left open and undisturbed.

Though not specifically stated open soil areas were considered a sign slovenlyness, something not tolerated in my upbringing environment. Somewhat along the line of "There are no dirty or lazy Zimmerman's". Something my maternal grandmother used to say.

The two main threats to most pollinators include habitat loss and pesticide use.

You can create a welcoming environment to ground nesting bees by doing the following:

1. Leave bare patches of ground in your garden or yard to help provide nesting sites. It may look unkempt but it is unkempt with a purpose.

2. Plant a variety of bee friendly nectar and pollen rich native plants. A good place to start is "Plants for Minnesota Bees" by Elaine Evans.

Elaine Evans

Photo 1: Plants for Minnesota Bees (front)

Elaine Evans

Photo 2: Plants for Minnesota Bees (back)

3. I have decided that to the extent possible I would rather watch what is happening in my garden then attempt to kill certain pests with the high likelihood of killing beneficials. My worst garden pest is the fourlined plant bug which attacks my anise hyssop. Given how I feel about anise hyssop (possibly the best bee plant I have encountered) you can imagine how motivated I would be to remove these pests. I have controlled them to my satisfaction by clapping my hands on the leaves where I see the bugs. The leaves tolerate this much more than the fourlined plant bugs. Avoiding the use of synthetic pesticides in your garden and on your lawn is recommended.

Don't Confuse Yellowjackets and Bees

Jeffrey Hahn, Extension Entomologist

Jeff Hahn, Univ of MN Extension

Photo 1: Yellowjackets are black and yellow with few hairs and construct nests made of a papery material.

As the summer winds down, people have been commonly finding insects nesting in and around their homes. There can be confusion whether people are seeing yellowjackets or honey bees. There is tendency for people to call all stinging insects "bees". This has been compounded with the recent attention in the media on honey bees so people are thinking about them even more. While yellowjackets and honey bees both can sting, they have very different biologies. At this time of the year, people are most often seeing yellowjackets.

Jeff Hahn, Univ of MN Extension

Photo 2: Honey bees are brown and black and hairy. Don't confuse them with yellowjackets.

A yellowjacket is about ½ inch long (this can vary some), black and yellow, and relatively slender with few hairs. A baldfaced hornet, actually a kind of yellowjacket, is a little larger, about 5/8th inch long, and mostly black. Honey bees are about ½ inch long brown and black, relatively slender but have more hair.

Yellowjackets construct their nests from a papery material with the combs surrounded by an envelope, while honey bees produce combs made of wax. Yellowjacket nests can be aerial, e.g. hanging from trees or attached to buildings; hidden in cavities, such as wall voids in buildings; or subterranean e.g. constructed in old rodent burrows. In cases where the nest is hidden or subterranean, a person can see the yellowjackets flying in and out of an opening but cannot see the nest.

Honey bees typically nest in artificially constructed hives. It is possible for them to nest in cavities in homes but this is not very common. While honey bees don't nest in the ground, bumble bees do. Bumble bees are stout, robust insects, usually black and yellow, and hairy. Both yellowjackets and bumble bees have annual nests, i.e. they last one year; they die when freezing temperatures arrive in the fall. However, honey bees have perennial nests which survive the winter and can live for multiple years.

Dan Martens, Univ of MN Extension

Photo 3: While people wonder if nests like this are bee hives, the papery material it is constructed from tells us this belongs to yellowjackets

It is very important to distinguish between yellowjackets and bees. If people believe they have honey bees, they may take steps to try to protect the nest or even try to have it moved despite the potential risk of stings. While it is true beekeepers can remove and relocate honey bees from a nest (if you have a confirmed honey bee nest around a home, contact the Minnesota Hobby Beekeepers Association), they do not want to and will not get involved with a yellowjacket problem. While yellowjackets are beneficial because they are important predators, they do minimal pollinating and do not need to be saved.

If you have a yellowjacket nest on your property, there are several options for dealing with it. If the nest is located a reasonably safe distance from where people may be present and the risk of stings is minimal, then just ignore it. Eventually, all of the insects in the nest die after hard frosts occur.

If a yellowjacket nest is present and you want to control it, keep a few things in mind. First, treat the nest during late evening or early morning when the yellowjackets are least active; this will help minimize the chance of stings. If after a day there is still activity, i.e. yellowjackets are still flying in and out, then repeat the treatment. If you are uncomfortable treating a yellowjacket nest, it is always an option to hire a pest management professional to deal with it; they have the experience and the appropriate tools to expertly eliminate nests.

Jeff Hahn, Univ of MN Extension

Photo 4: Yellowjacket commonly nest in the ground too!

When yellowjackets are nesting in the ground, the most effective means of controlling them is with a dust labeled for ground dwelling insects; the workers get the dust on their bodies and carry into the nest spreading it to the rest of the colony. Pouring a liquid insecticide into the nest entrance is less likely to be effective as the liquid may not reach the nest depending on where it is located within the burrow

Jeff Hahn, Univ of MN Extension

Photo 5: Hidden yellowjacket nests are tricky to control for residents; they should hire a pest management professional to do this type of job.

If you can see the nest, e.g. it is attached to the eaves, use a wasp and hornet aerosol spray and treat directly into the nest. However, yellowjacket nests that are found inside homes in wall voids, attics, concrete blocks, or similar spaces are much more challenging to control. An aerosol insecticide is not very effective. In fact, an aerosol spray can sometimes cause the yellowjackets to look for another way out, which often leads them to the inside of homes. Also, don't seal the nest opening until you know all of the yellowjackets are dead as this can cause the same reaction. It is usually best for a pest management professional to control hidden nests in buildings.

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).

Butterflies in slow motion flight

Karl Foord, Extension Educator - Horticulture

I recently took a class on bee identification at the Southwest Research Station of the Museum of Natural History in the Chiricahua Mountains three hours west of Tucson, Arizona.
While traveling to one of the bee collection sites we passed a large puddle along the road. Two days previously a heavy downpour had soaked the countryside and this puddle downstream from an open cattle range provided the butterflies with water, sodium, and perhaps other needed nutrients.

I have always wondered about the flight of butterflies. Their flight often seems quite erratic. I understand this to be part of a strategy to avoid predators. Is their flight actually as erratic as it appears to us?

I returned to the puddle the following day and was happy to see that it was not completely dry. I was able to slow down their flight with a high speed camera capturing 3500 frames per second. If 30 frames per second is what we consider to be normal then this slows down the flight by a factor of 117.

What was seemingly erratic now seems quite graceful. Wouldn't you agree?

Notice how the wings curl to provide lift on both the forward and backward strokes of the wings. Also notice how the butterflies wing strokes are not constant and that they often drift before beginning a new stroke. Access the video at Butterflies in slow motion flight

Please enjoy the ballet.

Just Wait Out Foreign Grain Beetles

Jeffrey Hahn, Extension Educator

Jeff Hahn, Univ. of MN Extension

Photo 1: Don't confuse tiny foreign grain beetles for flies or fleas

Very small, brownish beetles are being found in some buildings, especially homes that have been recently constructed. Proper identification is critical as these beetles may be confused for other insects, such as fruit flies, drain flies, or fleas. A foreign grain beetle is about 1/12th inch long and reddish brown with a flattened body.

Foreign grain beetles can also fly which is why they might be confused for small-sized flies. However, foreign grain beetles have a generally harder body compared to the softer bodied flies. Fleas also have a relatively hard body but are fattened instead from to side to side; fleas are also wingless and can't fly.

The favorite food of foreign grain beetles is fungi and so they are typically found in relatively damp areas. They are often associated with new construction because the moisture in wall voids when construction is first completed in conducive for fungi which then provides a food source for the foreign grain beetles. Despite their name, foreign grain beetles are not typically found infesting food products in homes. They prefer to attack old, moldy grain products.

Fortunately foreign grain beetles are only a temporary nuisance. Adult beetles are active during late summer and early fall and then go away on their own. The beetles will survive only for one or two years in a home before it becomes too dry to support fungi and the beetles. Tolerate foreign grain beetles until they go away on their own. The best control is physical removal, e.g. with a vacuum. Insecticides do not prevent foreign grain beetles from appearing and their use is not recommended.

Click here for more information on foreign grain beetles.

Shake Rattle & Role: BUZZ Pollination

Karl Foord, Extension Educator - Horticulture

I recently had the rare privilege of traveling to Tucson, Arizona to visit the laboratory of Dr. Dan Papaj. I worked with Dr. Stephen Buchmann (author of several fine books) and Avery Russell to photograph buzz pollination of Solanum species flowers by the Common Eastern Bumble Bee (Bombus impatiens).

Buzz pollination occurs when an insect visiting a flower uses vibration to extract pollen from the anthers of a flower. This is accomplished by the insect activating their wing muscles without flying. This vibration shakes the anthers of the flower causing pollen to pore out the end of the anther; anthers having pores at their end are called porical for this reason.

This is not an isolated occurrence as some 15,000 to 20,000 plant species have pores or slits at the end of their anthers. Also some 50 genera of bees possess the capability to accomplish buzz pollination. Interestingly enough, honey bees are not capable of buzz pollination.

Poricidal anthers are often found on flowers that also lack nectaries, and flowers that have developed anthers of different lengths facilitating pollen dispersal on the pollinating insect.

Middle C on the piano is 262 Hz (beats per second) and A above middle C is 440 Hz (the tone orchestras use to tune their instruments). The peak frequency used in buzz pollination is in between these two frequencies at 330 Hz. Buzz pollination also produces lesser peaks at the five harmonic frequencies above 330 e.g. 660, 990, 1320, and 1650.

I have produced a video of buzz pollination filmed with a high speed camera that allows one to actually see the shaking of the bee. Under normal circumstances this would only be visible as a blur. The bees were filmed at 1,000 frames per second meaning that they have been slowed down by a factor of 33.3.

Please enjoy the video!

EAB Found Near Rochester

Jeffrey Hahn, Extension Entomologist

Jeff Hahn, Univ. of MN Extension

Photo 1: Watch for EAB and symptoms of infested trees. In this picture is an EAB larva the S-shaped tunnels it makes.

The Minnesota Department of Agriculture (MDA) announced earlier this week that emerald ash borer (EAB) has been confirmed in Olmstead County south of Rochester. Olmstead County is now the fifth county in Minnesota to confirm EAB (Ramsey, Hennepin, Houston, and Winona counties being the others). The infestation was found near the interchange of Interstate 90 and Highway 63, about 45 miles from the nearest known EAB infestation. It is believed that EAB were accidentally moved with human assistance into this area.

Because of this infestation, Olmstead County is now under Federal and State quarantine. This quarantine restricts the movement of ash material, including branches and logs, and all hardwood firewood. More information about the EAB quarantine and regulatory restrictions can be found here.

Jeff Hahn, Univ. of MN Extension

Photo 1: The best way to slow down EAB is to NOT move firewood. Buy it where you burn it!

It is critical that residents don't move firewood, especially out of quarantined areas. Buy firewood locally from approved vendors and burn it where you buy it. By itself, EAB only travels a mile or two a year. However, when people inadvertently move infested wood, EAB can travel many miles at a time.

People can also help in the fight against EAB by being familiar with what EAB looks like and the symptoms of infested trees.  Residents should report any insects suspected to be EAB or ash trees they believe are infested with EAB to the MDA; leave a voice message at 1-888-545-6684 or e-mail  

More information on EAB can be found on the Extension's EAB page

Pollinator Habitat

Karl Foord, Extension Educator - Horticulture

Karl Foord

Photo 1: Home landscape

Karl Foord

Photo 2: Home landscape

Karl Foord

Photo 3: Home landscape

Karl Foord

Photo 4: School landscape

Karl Foord

Photo 5: School landscape

Karl Foord

Photo 6: Business landscape

Karl Foord

Photo 7: Industrial landscape

Karl Foord

Photo 8: Industrial landscape

Karl Foord

Photo 9: Roadside setback for industrial landscape

Karl Foord

Photo 10: Undeveloped area

Karl Foord

Photo 11: Wild Bergamot (Monarda fistulosa) with bumblebee

Karl Foord

Photo 12: Hoary Vervain (Verbena stricta) with bumblebee

One of the factors in the decline of pollinators is the loss of habitat. To get a sense of this I took the position of a bee looking for forage. I drove my car from my house through my neighborhood in Chaska, Minnesota around the Chaska Middle School out to Hwy 41 and north toward Hwy 5 and the Minnesota Landscape Arboretum.

What I found in this casual survey was a preponderance of turf in the landscape. The homes had most turf surroundings with a few shade trees and low maintenance foundation shrubs. There were a few flowers to accent a rock or a mailbox. Often these plants were not attractive to pollinators such as daylilies. The businesses had turf and accented their signs with rocks and low maintenance plants. The industrial area was completely dominated by turf and shade trees, and contained no cultivated flowers.

The place where I found bee forage was in refuse areas or undeveloped areas. Here I found typical weeds such as thistle (Cirsium spp.), Queen Anne's Lace (Daucus carota), Bird's Foot Trefoil (Lotus corniculatus) among others. I also found Wild Bergamot (Monarda fistulosa), Hoary Vervain (Verbena stricta), and Grey-headed Coneflower (Ratibida pinnata). The majority of bees including bumble bees and other natives were working the beebalm and the vervain, predominantly.

Incidently the richest area was the undeveloped area along Hwy 41. I was informed that this was destined to be developed.

As a bee searching for forage this is rather discouraging with the future looking even more bleak. All things considered it still looks like one of the more promising solutions is to follow Dr. Marla Spivak's exhortation to plant flowers and specifically those that provide nectar and pollen to our pollinators.

There are many subtle and complex interactions between plants and their pollinators.
Can our combined urban spaces be designed in such a way as to substitute for the loss of natural areas as we humans continue to expand?

I do not know. However, it is in our best interest to try. As Marla says, "Plant Flowers!".

Fall Webworms are Active Now

Jeffrey Hahn, Extension Entomologist

Harold Revoir

Photo 1: Fall webworms can detract from a tree's appearance but does little actual damage to it.

While most caterpillars are active during the spring, there are a few that are not feed until summer. Fall webworm caterpillars, Hyphantria cunea are first active during late July and can be found feeding into September. This caterpillar varies in color from pale green or yellow with two rows of black spots on its back with long fine white hairs.

However, an easy way to identify fall webworms is from the webbing they produce that covers the ends of branches. The caterpillars remain inside this webbing to feed on the leaves. The feed on a wide variety of hardwood trees (over 100 trees and shrubs), including black walnut, oak, birch, elm, ash, willow, cottonwood, and chokeberry.

Typically fall webworms attack large, mature trees and their feeding is minor and does not have any lasting effect on trees. Occasionally small trees are attacked; they can be severely defoliated and can even be completed encased by webs. The primary problem is to the appearance as the webbing can be unsightly. However, after fall webworms are done feeding the webbing eventually deteriorates and goes away on its own.

In the majority of cases, a fall webworm infestation can be ignored, especially if it is in a large, mature tree. Direct insecticide treatments are not effective as the webbing protects the caterpillars from sprays. It is possible to effectively spray fall webworms when the caterpillars first hatch and the webbing is still small, although people don't usually notice them then. If the webbing is within reach, it can be physically pulled out along with the caterpillars. Even if you don't get the entire webbing out, you can still knock many of the caterpillars out of the nest. Do not try to burn the webs; this is more harmful to trees than any control that is achieved.

Strawberry Root Weevils

Jeffrey Hahn, Extension Entomologist

Jeff Hahn, Univ. of Minnesota Extension

Photo 1: Strawberry root weevils are common now - don't confuse them for bed bugs

A strawberry root weevil, Otiorhynchus ovatus, is a common insect during July and August. It is small, 1/4th inch long, and dark brown to black. It is pear-shaped or light bulb-shaped with a short broad snout. It also has rows of punctures on its wing covers. A strawberry root weevil cannot fly.

As a larva, a strawberry root weevil feeds on the roots of a variety of plants, including, arborvitae, spruce, and strawberries. As an adult, it feeds on the edge of leaves. Strawberry root weevils sometimes can accidentally enter homes and other buildings. It is common to find them around sources of moistures, such as sinks and tubs. They do not cause any damage and are just a nuisance. In most cases, people see only a few weevils but there are times where homes can be plagued by large numbers of strawberry root weevils.

In addition to being a nuisance, strawberry root weevils are sometimes confused for bed bugs causing much consternation until the insect is correctly identified. A bed bug is more round in shape and lacks the snout and the punctures on its back that a strawberry root weevil possesses. It is always a good idea to have an insect correctly identified by an expert if it is suspected to be a bed bug. Strawberry root weevils are also sometimes confused as ticks because the antennae looks like a pair of legs.

Physical removal is the only necessary control. Strawberry root weevils will eventually go away on their own. For more information, see Home-invading weevils.

Watch for Masked Hunters

Jeffrey Hahn, Extension Entomologist

Jeff Hahn, Univ of Minnesota Extension

Photo 1: Masked hunter adult - they can bite if you are not careful

Some people have been encountering a 3/4 inch long, dark colored, somewhat slender insect in their homes lately. This insect is a masked hunter, Reduvius personatus, a type of assassin bug (family Reduviidae). A masked hunter is a predator, feeding on a variety of insects. It can accidentally wander into homes during summer and is considered to be just a nuisance invader. No more than a few are usually seen at a time.

Fortunately, a masked hunter is not aggressive towards people, although it is capable of inflicting a painful bite if it feels threatened. It also is not a carrier of any disease. This is important as a masked hunter has been confused with kissing bugs which do transmit Chagas disease. Chagas disease is a potentially serious illness caused by a protozoan organism.

Kissing bugs also belong to the assassin bug family which helps explain the confusion between them. However, while kissing bugs belong to the subfamily Triatominae, masked hunters are in the Reduviinae subfamily. Kissing bugs are found in South America, as well as Central America and southern Mexico and are not native to the U.S. They get their name because of their habit of biting people on the face at night.

There is not any special control for masked hunters. Physical removal is the only necessary action that needs to be taken. If possible, capture and release any found outdoors. For more information, see Masked hunters.

Pseudoscorpions are Curious, Harmless

Jeffrey Hahn, Extension Entomologist

Bunni Olson, Univ. of MN Extension

Photo 1: Pseudoscorpions look fierce but are harmless to people

A small, 1/5th inch long, reddish or brownish 'bug' with two large 'pinchers' is sometimes found in homes. Although it looks like a tick or scorpion, it is actually a pseudoscorpion. A pseudoscorpion is not an insect but is a type of arachnid, so it is related to spiders, ticks, and true scorpions. Pseudoscorpions have eight legs and pincher-like pedipalps (part of their mouthparts). They lack the stinger that true scorpions possess.

Pseudoscorpions are predators on a variety of small insects and other arthropods, like springtails, booklice, and mites. They are found in a variety of habitats, such as leaf litter, moss, and under stones and tree bark, and occasionally buildings. Despite their appearance, they are harmless to people. If you find a pseudoscorpion in your home, just physically remove it or ignore it. If possible, capture and release it outdoors. Fortunately, we rarely see more than one or two pseudoscorpions at a time. For more information, see Pseudoscorpions in homes.

Gypsy Moth Quarantine in Minnesota

Jeffrey Hahn, Extension Entomologist

(The following has been slightly modified from a June 30, 2014 news release from the Minnesota Department of Agriculture (MDA).

Bill McNee, Wisconsin Dept of Natural Resources

Photo 1: Lake and Cook counties are now under quarantine for gypsy moth

Due to the high number of gypsy moths trapped in northeast Minnesota in 2013, the Minnesota Department of Agriculture (MDA) has placed Lake and Cook counties under quarantine effective July 1, 2014.  This is the first time a quarantine for gypsy moth has been established in Minnesota.  A quarantine helps to prevent gypsy moths from being moved by human activity to uninfested counties.

Outdoor items in the quarantined counties, like logs and firewood, camping equipment and patio furniture, that could be infested with gypsy moth must be inspected and certified as gypsy moth-free before moving to a non-quarantined area. This is done in two ways:

  • Homeowners, campers and others who live in and visit the proposed quarantine will need to self-inspect outdoor household items, like RVs, camping equipment and patio furniture, before moving those items out of the quarantine.
  • A compliance agreement allows items regulated by the U.S. Department of Agriculture (USDA), including firewood, pulp wood, and saw logs, to move out of the quarantine area or to be received by a business or individual outside Lake and Cook counties. The compliance agreement outlines practices for safe handling, transportation and storage to mitigate the spread of gypsy moth. Compliance agreements are documents prepared and agreed to by the company, city, county, agency, or organization interested in moving the regulated article and the MDA, or USDA in the case of interstate movement.

The MDA has been tracking and treating gypsy moth in Minnesota for decades. Since April 2013, MDA staff has been in discussions with the timber and nursery industries, as well as local, state, federal, and tribal officials on a potential quarantine. When 2013 trapping results showed a record number of gypsy moths, 90 percent of which were located in Lake and Cook counties, an advisory group recommended a quarantine of the two northeastern most counties in the state to the Commissioner of Agriculture.

Details of the quarantine can be found at here.  For questions on gypsy moth or the quarantine, call MDA's Arrest the Pest Hotline at 888-545-6684 (voicemail) or email 

Japanese Beetles Have Arrived

Jeffrey Hahn, Extension Entomologist

Japanese beetles have started showing up in gardens; the first discoveries of them were made in late June. It does not appear the late spring slowed down their emergence too much as the first week of July is about when we expect to see these beetles. It will be interesting to see how abundant they are this year. Because they were well insulated under the snow, it is not expected that last winter's cold weather had much effect on their populations.

However, a factor that does impact their relative numbers is the soil moisture at the time eggs are laid. The eggs and young white grubs are particularly susceptible to dry soil conditions. Eggs are laid soon after adults start to emerge, generally early to mid-July. However, older grubs are much more tolerant of dry soil. So the number of Japanese beetles that are present this year is related to soil moisture last summer. Although we have experienced drought in many recent years, 2013 was a fairly wet year. We could expect Japanese beetle numbers to be rebounding in at least in some areas.

Jeff Hahn, Univ. of MN Extension

Photo 1: Handpicking Japanese beetles on daily basis and putting them in soapy water can effectively reduce feeding injury on plants.

There are a variety of methods for managing Japanese beetles including physical removal. A research paper in Horticultural Entomology from this year examined the effectiveness of handpicking Japanese beetles daily on a small scale (i.e. a home landscape). This research looked particularly at the effectiveness of removing Japanese beetles at different times of the day.

The researchers found that physically removing Japanese beetles on a daily basis in general helped to significantly reduce damage on grapes compared to removing no beetles. This is because damaged leaves give off a chemical volatile which attracts Japanese beetles and increases colonization and damage to plants. Keeping numbers of Japanese beetles low helps to reduce the attractiveness of them to plants. The researchers additionally found that the best time to remove Japanese beetles is at 7:00 p.m. (compared to 8:00 a.m. and 2:00 p.m.). This is because Japanese beetle activity peaks in mid-afternoon and feeding continues overnight. Grape leaves damaged overnight were more effective in recruiting new Japanese beetles than freshly injured ones. Reducing Japanese beetles at this time was the most effective time to minimize feeding injury to plants through physical removal.

Jeff Hahn, Univ. of MN Extension

Photo 2: If you have had problems with Japanese beetle grubs, treat them preventatively now.

If you have had a problem with Japanese beetle grubs in the past, now is the best time to treat them preventatively. 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.

For those looking for a low impact approach to treating white grubs, consider parasitic nematodes, especially Heterorhabditis species. Apply nematodes late in the evening. Be sure that they are watered in and that the soil is kept moist for at least a week (two to three weeks is even better). Parasitic nematodes are available from garden catalogs or biological control companies. Milky spore disease is also a low impact insecticide; however in research trials it has not been very effective against Japanese beetle grubs.

There are several traditional preventative insecticide options that are very effective. Look for imidacloprid (various trade names) or clothianidin (Green Light Grub Control with Arena), both neonicotinoids, or chlorantraniliprole (Scott's GrubEx) a type of anthranilic diamide. If Japanese white grubs are not treated preventatively now, they can be treated curatively with Trichlorfon (Dylox) or chlorantraniliprole (Scott's GrubEx) until mid to late August. After that, the grubs are generally 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.

For more information see, Japanese beetle management in Minnesota.

Squash Vine Borers are Out Now

Jeffrey Hahn, Extension Entomologist

Jeff Hahn, Univ. of MN Extension

Photo 1: Mating squash vine borer adults

Squash vine borer adults have just been sighted. If you are growing summer squash, winter squash, or pumpkins, take the proper precautions to protect your vine crops from this insect. This garden pest less frequently attacks butternut squash, cucumbers and melons. If you are unsure whether squash vine borers are in your area, monitor your garden for their presence.

Set out a yellow pan of water. Yellow is attractive to squash vine bores, and they will fly to and fall into the water. Check these traps at least once a day. Squash vine borer adults are easy to recognize as they are wasp-like and about ½ inch long. They have an orange abdomen with black spots and the first pair of wings is metallic green while the back pair of wings is clear. These moths are active during the daytime and you may also observe them when you are in your garden.

Management of squash vine borers is often challenging. There are several steps you can take to try to minimize them, such as planting less attractive crops, making a later, second planting, using row covers (note: do not use row covers if planting vine crops in the same site in consecutive years), and well-timed insecticide treatments. For more information on squash vine borers, including management, see Squash vine borer management in home gardens

Don't be Fooled by Fungus Killed Flies

Dori Eder

Photo 1: Fungus killed flies on grape. Despite any circumstantial evidence, they are incapable of damaging plants.

People are finding a curious insect in their gardens and yards now. Grayish black flies, about ¼ inch long, are being found clinging to the leaves and stems of a variety of different plants. Their legs and wings are typically splayed out in odd, unnatural positions. If you watch the fly carefully, you will notice it doesn't move. That's because it's dead - it has been killed by a fungus that is specific to these flies.

This fungus has been particularly common this year due to the abundant rainfall we have experienced throughout much of Minnesota. When seed corn maggot flies become infected with this fungal disease, they usually fly to a plant or other object and climb up. Eventually they die, leaving their legs and wings in whatever position they were in at the time of death. Additionally, their mouthparts are often extended out. In recently infected flies, the abdomen is swollen and whitish, with fungus protruding between the body segments.

When these flies die on a plant that is damaged, it seems reasonable to blame them for this injury. However, seedcorn maggot flies do not feed on plants (in fact there are no adult flies in Minnesota that directly feed on plants). They are just a curiosity and should be ignored.

Rose Chafers are Here

Cindy Schmid

Photo 1: Rose chafers on peony flowers.

Rose chafers are out in full force right now. If you live in an area with sandy soil, you are much more likely to see them in your garden. These scarab beetles feed on a variety of plants but are particularly interested in the flowers of roses and peonies. They can also feed on the leaves of a variety of plants. Rose chafers feed for about three to four weeks; we can expect to see them into early July. There are several options for dealing with this beetle including handpicking and the judicious use of insecticides. For more information, see Rose Chafers.

Start Trapping for Spotted Wing Drosophila

If you grow raspberries, strawberries, cherries, blueberries, or other susceptible soft-skinned fruit, start a trapping program to monitor the potential presence of spotted wing Drosophila (SWD). A single SWD has been detected on June 6 in a trap set on the University of Minnesota St. Paul campus. Last year, the first SWD was trapped on June 27. It is safe to assume that SWD are present throughout the state.

Jeff Hahn, Univ. of MN Extension

Photo 1: Use traps to detect spotted wing Drosophila's presence.

Home gardeners can monitor SWD with homemade traps. Use a large plastic cup with a cover and make several 3/16th inch diameter holes near the top. Put one to two inches of apple cider vinegar into the cup. Add either a yellow sticky card slightly above the vinegar or a little bit of liquid soap, such as dish soap. Hang traps on branches in a shaded location near fruit. Check traps at least once a week, replacing the sticky card (if used) and apple cider vinegar bait. Dispose of the old apple cider vinegar away from the trap location.

Early detection is very important when dealing with SWD as they can rapidly reproduce to large numbers and damage fruit. Management is a three pronged approach, monitoring (trapping), sanitation, and insecticide treatments. For more information about SWD including management, see Spotted wing Drosophila in home gardens.

The following list is updated with links to new and revised online Extension publications as they become available. 

June 17, 2014

General/Curiosity Insects (NEW!)
A new addition to the Extension Y&G diagnostic tool "What insect is this?" Find information to help identify and understand insects (1) with obvious wings (flies, wasps, moths, etc.) and (2) insects without obvious wings (beetles, bugs, ants etc.).

May 27, 2014

Carpenter ants (revised)
Bronze birch borer and twolined chestnut borer in Minnesota (revised)
Maple petiole borer
Nightcrawlers (revised) 

December 2, 2013

Pest management in the home strawberry patch (new)
Pest management for home blueberry plants (new)
Integrated pest management for home raspberry growers (new)
Integrated pest management for home stone fruit growers
Leafminers in home vegetable gardens

August 26, 2013

Masked hunters (revised)
Fourlined plant bug in home gardens (revised)

July 16, 2013

"Annuals" have been added to What's wrong with my plant? diagnostic tool.

June 18, 2013

Root maggots in home gardens (new)
Emerald ash borer in Minnesota (revised)
The Extension EAB web page has also been revised

May 23, 2013

Anthracnose (revised)
Powdery Mildew
Cedar Apple Rust and Other Gymnosporangium Rusts
Crown Gall (revised)

Managing Apple Scab on Ornamental Trees and Shrubs
Managing Impatiens Downy Mildew in the Landscape (new)

Managing Impatiens Downy Mildew in Greenhouses, Nurseries, and Garden Centers
Basil Downy Mildew

May 1, 2013

Aphids on Minnesota Trees and Shrubs (revised)
Woolly Aphids on Minnesota Trees and Shrubs (revised)
Spotted Wing Drosophila (new)
Two-spotted Spider Mites in the Home Garden and Landscape (new)

Cabbageworms are Active Now

Jeff Hahn, Univ. of MN Ext

Photo 1: Watch for cabbageworms on your cole crops.

Are you growing any cole crops, such as cabbage, broccoli, kale, radish, or turnip, in your garden? If you are, it's a good idea to check them out for imported cabbageworms. As an adult, imported cabbageworms are pretty white butterflies. As a caterpillar these larvae are light green with thin yellow stripes running down their body; a series of short hairs gives it a velvety appearance. It's the caterpillar stage that damages plants by chewing holes in the leaves, sometimes seriously defoliating them.

These crops can tolerate some feeding. However young seedlings and transplants are particularly susceptible to feeding injury and should be protected. Checking plants regularly is very important so any infestations can be spotted quickly to minimize injury. If any imported cabbageworms (and cabbage loopers later in the summer) are discovered, there are several options for dealing with them, including handpicking and using the low impact insecticide Bacillus thuringiensis. For more information, see Caterpillar pests of cole crops in home gardens.

Don't Confuse Sixspotted Tiger Beetles with EAB

Jeffrey Hahn, Extension Entomologist

Jeff Hahn, Univ. of MN Extension

Photo 1: Sixspotted tiger beetle, a common insect in May and June.

The sixspotted tiger beetle is a native insect found throughout most of Minnesota commonly in deciduous forests, along the edges of woods, and in adjacent fields. It can even be found in urban areas in yards and gardens. Watch for this beetle at or near the ground in areas where the sun shines.

This beetle measures about ½ inch in length. It really stands out because it is an iridescent green or blue-green. It also has six white spots, although that number can vary. The sixspotted tiger beetle has conspicuous sickle-shaped mandibles (jaws) and large bulging eyes on the side of its head.

The six-spotted tiger beetle is present in Minnesota from May into early July. It is very active, moving rapidly in short bursts. It is common to see it run rapidly or fly a short distance. As one might suspect from the large eyes and the powerful jaws, this insect is a predator on all types of insects.

Jeff Hahn, Univ. of MN Ext

Photo 1: Emerald ash borer, a slimmer and slower insect than a sixspotted tiger beetle

Besides being colorful and a fun insect to observe, a sixspotted tiger beetle is also important because people may mistake it for an emerald ash borer (EAB), a destructive invasive insect that infests and kills all species of ash. They are both a similar size and bright, iridescent green.

These two insects can be distinguished by the shape of their bodies; EAB is slender, gradually tapering to the tip of its abdomen while the wing covers of a sixspotted tiger beetle are wider than its head. Also a sixspotted tiger beetle is much faster than an EAB.  See also EAB look-a-likes.  If there is any doubt whether an insect is an EAB, capture it and take a picture and submit it to "The Arrest the Pest Line",

Karl Foord, Extension Educator - Horticulture

Karl Foord

Photo 1: Andrenid Bee on Willow Flower

Karl Foord

Photo 2: Andrenid Bee on Prunus flower

Karl Foord

Photo 3: Andrenid Bee on apple flower

Karl Foord

Photo 4: Andrenid Bee and blueberry flowers

Karl Foord

Photo 5: Andrenid bees on raspberry flowers

Andrenid bees are one of the earliest emerging bees in the spring. You can see them on willow flowers depending on the type of spring (Photo 1), and we had such a spring this year. Following willows the Andrenids will often be found on Prunus species (plums & cherries) (Photo 2). The next trees and shrubs to flower are apples (Photo 3), blueberries (Photo 4), and raspberries (Photo 5). Andrenid bees are important native pollinators of these species. The next time you put blueberries on your breakfast cereal or make raspberry jam, remember that Andrenid bees have played a significant role in the creation of those fruits.

Karl Foord, Extension Educator - Horticulture

Karl Foord

Photo 1: Honey bee watering hole

Karl Foord

Photo 2: Honey bees hovering around watering hole

Karl Foord

Photo 3: Honey bees hovering around watering hole

Karl Foord

Photo 4: Honey bee hovering while drinking

Karl Foord

Photo 5: Honey bee drinking on edge of puddle

If you think back to last Friday May 30 2014, it was a hot day with temperatures in the high 80's. I was observing pollinators in the apple trees at Pine Tree Apple Orchard. They were draining a low area of one of the fields and in the process created a puddle (Photo 1) just across the field road from a number of honeybee hives. This was a perfect opportunity for the bees to gather around the watering hole, if you will. The bees would hover around the hole looking for a good place to land without getting wet (Photos 2 & 3). One honeybee hovered while she drank (Photo 4), but all the others landed prior to drinking (Photo 5).

Insects on the Loose: What's in Your Garden?

Jeffrey Hahn, Extension Entomologist

Jeff Hahn, Univ. of Minnesota Extension

Photo 1: Crucifer flea beetle and its feeding damage.

There are a variety of insects that are active now and could be in your garden. When you are inspecting your garden for pests, keep an eye out for these insects.

Flea beetles are very small, 1/16th - 1/8th inch long. They are usually dark colored although some can have red or yellow on them. An easy way to identify flea beetles is that they can jump. Flea beetles attack a variety of vegetables, including beans, broccoli, cabbage, potatoes, squash, and radish. Flea beetles chew shallow pits and small holes into leaves. This feeding can be particularly damaging to seedlings and cole crops. Go here for more information on flea beetles, including management.

Jeff Hahn, Univ. of Minnesota Extension

Photo 2: Colorado potato beetle larvae on eggplant.

Colorado potato beetles overwinter as adults and start to lay eggs in the spring. The adults are broadly oval in shape with yellowish to cream colored wing covers with ten thin black stripes. The larvae are pinkish with a humpbacked larva body. Both the adults and larvae feed on the leaves of not only potatoes but also eggplant, tomato, pepper, and similar plants. Potato tubers can be adversely affected when defoliation is severe. Go here for more information on Colorado potato beetles, including management.

Jeff Hahn, Univ. of Minnesota Extension

Photo 3: Fourlined plant bug nymph and its damage.

Also watch for fourlined plant bugs. They overwinter as eggs and emerge in the spring as small bright red immature insects (nymphs) with black wing pads. They eventually turn into yellow green insects with four black stripes. Fourlined plant bugs use their piercing - sucking mouthparts to feed on the foliage of a wide variety of plants including perennials. Their feeding causes a series of small, dark, shallow pits on the leaves. Fortunately, this feeding normally does not kill the plant although it can affect its appearance. Go here for more information in fourlined plant bugs.

European Pine Sawflies are Active Now

Jeffrey Hahn, Extension Entomologist

Do you have a pine, especially a mugo, Austrian, jack, or red pine, in your yard? Now is a good time to check it for European pine sawfly activity. These insects are caterpillar-like with black heads and gray green bodies and dark green stripes (when they are young the dark green stripes may not be visible). While they are relatively small now, they eventually will grow to be about one inch in length.

Jeff Hahn, Univ. of Minnesota Extension

Photo 1: Young European pine sawflies feeding gregariously.

Look closely for these insects as they are hard to see because they blend in so well with the needles. An advantage when inspecting for them is that they are gregarious, meaning that they occur in nonsocial groups, so there can be many feeding on a given branch (which easier to find than individual sawflies).

Your first clue that European pine sawflies are present could also be finding defoliation on branches. As feeding becomes more severe, it is usually easier to find the damage before seeing the insects. European pine sawflies feed from about mid-May through June on last year's needles. Fortunately, large trees are typically not injured, although it is possible for small trees or shrubs to be severely defoliated. There is only one generation per year.

Jeff Hahn, Univ. of Minnesota Extension

Photo 2: European pine sawfly defoliation. Note the missing needles and how some needles have turned brown and curled.

If you find European pine sawflies, first determine whether they are worth managing. If they are, there are a few options available to deal with them. First consider physically removing them. This can be done by wearing rubber gloves and running your hands up the branches, crushing the sawflies. There are several low impact insecticides that can be sprayed, especially insecticidal soap and spinosad. Keep in mind that Bacillus thuringiensis which effective against caterpillars does not kill sawflies.

Most contact, residual insecticides will work against sawflies. Because sawflies feed in groups, it is possible to spot treat infestations instead of treating entire trees. Examples of effective insecticides include permethrin, bifenthrin, and other pyrethroids, malathion, and carbaryl. Neonicotinoids, such as imidacloprid and acetamiprid, can also effectively manage sawflies. Apply imidacloprid and acetamiprid as sprays directly to the pine (Read the label directions of the specific product you intend to apply to ensure that it is used correctly).

These insecticides are hazardous to bees so don't apply them to flowering plants. Treat plants in late evening to minimize exposure to bees. 

Use caution when reading new bee and pesticide research

Jeffrey Hahn, Extension Entomologist

New research about bees and pesticides from Harvard University was recently published by Lu et al. in the Bulletin of Insectology. This research examined honey bee colonies that were fed high fructose corn syrup (HFCS) contaminated with two common neonicotinoids (imidacloprid or clothianidin) during late summer and then observed in the following spring. Both the control colonies and the insecticide exposed colonies did well going into fall. While both sets of colonies then declined, the control colony numbers rebounded while the insecticide exposed colonies suffered large losses. The authors' conclusions are that insecticides are the leading explanation for colony collapse disorder (CCD).

While this seems like compelling information on the surface, there are a number of concerns and flaws about this research that should cause readers to examine it very cautiously. The biggest concern for many is the concentration of insecticides which was fed to bees at a rate of 135.8 parts per billion (ppb), in a volume of 1.9 liters of sucrose water per colony per week, for 13 consecutive weeks. This is considered an extremely high concentration and does not represent a realistic rate of pesticide exposure to bees.

Jeffrey Hahn, University of Minnesota Extension

Photo 1: There are many factors implicated in the decline of bee health.

Interestingly, Dr Lu's own data in his 2012 research paper, also published in the Journal of Insectology, showed that at field-relevant dosages, neonicotinoids did not appear to harm bees (halfway through his research, he abruptly increased the dosage being fed to bees after it appeared that there was greater numbers of capped brood cells occurring when exposed to lower dosages).

The validity of his 2012 study is further held in question by the assumption that significant levels of residues are present in HFCS as a result of neonicotinoid seed treatment of corn, an assumption that was not tested. Eventually Dr. Lu et al. did look at this issue and in a 2013 published paper that found no neonicotinoid residues in any of the tested samples of HFCS and a maximum of 2.2 ppb of imidacloprid present in pollen. This would seem to contradict the premise used in pursuing any of this research.

Other red flags that have been raised include concern for the small sample size which did not allow for sufficient replication and does not allow for such broad conclusions that considers all geographic regions; the failure to fully explain the actual cause for the loss of one of the control colonies; and failing to thoroughly evaluate other commonly accepted stresses in CCD.

It is widely accepted that there are a variety of factors that influence bee health including parasites, diseases, loss of habitat (lack of flowers=poor nutrition), decreased genetic diversity, stresses due to beekeeper and grower practices, in hive pesticides, as well environmental pesticides. More research is needed to better determine which of these factors poses the most important threats to bee health.

Andrenid Bees Are Active Now

Jeffrey Hahn, Extension Entomologist

Jeffrey Hahn, University of Minnesota Extension

Photo 1: Andrenid bee searching for its nest

Andrenid bees are common in gardens and yards now. Common species are about ½ inch long with a yellow hairy thorax and a shiny black abdomen. Andrenid bees usually overwinter as pupae and emerge as soon as the weather becomes warm. Adults are relatively short-lived, surviving about a month.

Unlike honey bees and bumble bees which are social insects, andrenid bees are solitary with just one bee living in an individual burrow. However, they are also gregarious meaning that many nests can live close together. Andrenid bees like to nest in dry, sunny sites that contain sparse vegetation. People can become concerned when they see dozens of bees flying around a small area. Fortunately, these bees are very docile and nonaggressive and stings are very rare. People who are allergic to honey bee stings are not necessarily allergic to andrenid bees.

Tolerate andrenid bees as much as possible. They are valuable pollinators and all reasonable efforts should be made to preserve them. Because they like dry sites, you may be able to discourage them by keeping an area well-watered. Gardeners may also be able to work around them by working outside during the evening when these bees are less active. Remember, that these bees are active for only about a month and then go away on their own.

Karl Foord, Extension Educator - Horticulture

Karl Foord

Photo 1: Honey bee on dandelion

Karl Foord

Photo 2: Honey bee on Dandelion

Karl Foord

Photo 3: Split and curled stigmas of dandelion

Karl Foord

Photo 4: Dandelion stigmas & honey bee corbicula

Karl Foord

Photo 5: Native Mining bee (Andrena spp.)

Karl Foord

Photo 6: putative - Plasterer Bee (Colletes spp.)

Karl Foord

Photo 7: Native Small Carpenter Bee (Male) (Ceratina spp.)

For years I used to fight the dandelions in my lawn. I used herbicides and a small trowel. It was a bit of a losing battle as there is a third of an acre of school property adjacent to mine where dandelions are not controlled. This being separate from the nearby sports fields where the weeds are controlled. Imagine the number of dandelion seeds that blew into my yard each year.

As I have become more aware of pollinators, I have come to accept and perhaps even embrace the "noble" dandelion. Dandelions are an important source of pollen and nectar for bees early in the season when little else is flowering.

Given the problems facing our honey bees and native bees, it might be worth reconsidering dandelions and what they contribute to pollinator health. So with my new attitude I took camera in hand and ventured into the dandelion patch (Photo 1).

Consider how artistic is the dandelion flower when viewed close-up (Photo 2). The flowers each have split lobed stigmas that curl back and sometimes twist into shapes similar to the letter F shape holes cut into violins (Photo 3). Consider also the beautiful orange color of the dandelion pollen as attached to the corbicula or pollen basket of the honey bees (Photo 4).

The dandelion also provides nectar and pollen for our native bees: Mining Bees (Andrena spp.) (Photo 5), Plasterer Bees (Colletes spp.) (Photo 6), and Small Carpenter Bees (Ceratina spp.) (Photo 7). If you use your lawn for recreation and need a dense turf as a playing surface, you may want to control dandelions. However if this is not the way you use your turf, please consider letting some of the dandelions provide forage for our pollinators. In this way you can be a part of the solution to the ills facing our pollinators.

Karl Foord, Extension Educator - Horticulture

Karl Foord

Exhibit 1: Cucumber flowers

Exhibit 2: Cucumber flowers

Exhibit 3: Male squash bees in squash flower

Exhibit 4: Male squash bees in squash flower

The plant family Cucurbitaceae contains a number of our favorite garden plants. This includes: cucumbers, watermelon, muskmelon, pumpkins, squash, and gourds. This group is particularly fascinating in terms of its flower morphology. These plants are called monoecious because they have separate male and female flowers on the same plant (Exhibit 1). These flowers are most easily recognized by the shape of the stem below the flower. The stem below the female flower looks like a smaller version of the final fruit (Exhibit 2), and the stem below the male flower remains a single slender stalk.

Cucurbit flowers are short lived flowers that open a few hours after sunrise and are often closed by midday or early afternoon. Both male pollen viability and female stigmatic receptivity are at their highest when the flower opens and for the next few hours. Both pollen viability and stigmatic receptivity decrease significantly as the day progresses. It is important for the female flower to be pollinated as early in the day as possible.

In cucurbits there is one key concept: The quality of the fruit is a function of the number of seeds in the fruit. The number of seeds produced is a function of the number of viable pollen grains deposited on the stigma. The number of pollen grains deposited is a function of the number of visits by pollinators as well as by the type of bee visiting the flower. Expressed as an equation:

Quality of Fruit ~ # of seeds ~ pollen grains deposited ~ # of bee visits & type of bee

Because both male and female sexual parts are not in the same flower, pollen must be transferred from the male flower to the female flower. The pollen is too large and sticky to be transferred by wind and thus requires insect transfer. Bumble bees tend to deposit more pollen per visit than squash bees and squash bees tend to deposit more pollen per visit than honey bees.

To produce quality fruit watermelon need on the average 1,000 grains of pollen deposited, whereas pumpkin, cucumber and cantaloupe need between 300 and 400.

These flowers need to be visited multiple times (@ 10 - 12) by pollinators to achieve satisfactory pollen transfer and seed set.

Like the solanaceous crops in the previous article, these plants prefer higher temperatures and are sensitive to frost. Daytime temperatures in the high 70s or low 80s degrees and nighttime temperatures close to 65 degrees are optimum for seed set and growth. Poor fruit set or misshapen fruit can sometimes be the result of poor weather which has limited pollinator activity leading to poor pollination and insufficient seed set.

Another very interesting thing about squash flowers is that there is a bee that has evolved as a pollinator specific to squash flowers. Surprisingly enough this bee has been named a Squash Bee (Peponapis pruinosa). Another fun thing is that the male squash bees will often spend the night and parts of the day in the protected space created by the squash flower petals (Exhibits 3 & 4). So if you choose to grow squash you get the potential added treat of watching these very interesting bees.

In addition squash bees are solitary ground nesting bees who will often dig their ground nests in the garden near the squash plants. If you find holes in your garden that are a half inch in diameter, it could be the entrance to the squash bees nest. The linked article in the above paragraph has a picture of the entrance to a squash bee nest. If you encounter such a nest in your garden, one option would be to avoid tilling around this nest and encourage next year's squash bees. If you continue to plant squash every year you could end up with permanent residents.

Be on the watch for ticks!

Jeffrey Hahn, Extension Entomologist

Jeffrey Hahn, University of Minnesota

Photo 1: Adult female blacklegged tick. This tick is a potential vector of Lyme disease.

As the amount of time we spend outside increases, be aware that ticks are also active now. There are two common species of ticks in Minnesota, the blacklegged tick (also known as deer tick) and the American dog tick (also called wood tick). While the American dog tick is mostly a nuisance, the blacklegged tick can potentially vector diseases to people, especially Lyme disease.

Take precautions when outdoors, especially in areas where ticks are known to occur. Use repellents, especially DEET to protect against ticks. Also check yourself over carefully after being outdoors for any ticks that may have found you. Remember that a tick has to be biting to be able to transmit a disease; if it is unattached it cannot vector a disease

Jeffrey Hahn, University of Minnesota

Photo 2: Adult female American dog tick. This tick is not an important vector of disease, it is primarily a nuisance

If any ticks are found, it is important that they are correctly identified because blacklegged ticks are important disease vectors while American dog ticks are not. Color and size are not always dependable when identifying ticks and it may be necessary to have specimens identified by an expert.

Click here for more information on ticks and their control. You can also find information about tick diseases here.

Ignore ash flower galls

Jeffrey Hahn, Extension Entomologist

Jeffrey Hahn, University of Minnesota

Photo 1: Ash flower gall during early spring

At this time of year, ash flower is gall particularly conspicuous.  They are black or dark brown growths found on the branches of green ash.  Because of its unsightly appearance, some people assume that it also damages trees.  The good news is that does not affect the health of ash.  Research conducted at the University of Minnesota in the 1980's showed that the presence of galls did not impact tree health. 

Control of ash flower galls is not necessary.  It is also very difficult to obtain good management of these mites.  If treatment is attempted, try an application of dormant oil when the mites become active in spring prior to bud break (which will occur soon), although this will only be partially effective.  Ultimately the best bet is to just ignore ash flower galls.  Ash has much bigger problems with emerald ash borer being present and should be considered a low maintenance tree.

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 leisurely 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.

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