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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).

September 15th Yard and Garden News

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.

Thanks for listening!

We aren't always able to answer everyone's text'd questions on the air, so we try to post a few along with answers here in the Yard & Garden News blog. Remember that you can always visit the U of M Extension Garden website for loads of gardening resources.

Hope you join us and our host Denny Long every Saturday, 8-9am, on WCCO Smart Gardens and happy gardening!

Question: Paver stone patio on north side of house has mold / moss in between stones. How do I get rid of this?

Answer: You can use a sharp tool to scrape / dig out moss and fill in spaces with builders' sand. You can plant low-growing, creeping plants like creeping thyme or wooly time in the spaces.

Mold can be removed with a bleach / water solution and a wire brush. Be careful not to get bleach on the plants nearby, your clothing or patio furniture.

Question: I just planted a 2" Autumn Blaze maple. What are you recommendations for watering?

Answer: Here is an excerpt from the U of M Extension publication Planting and Transplanting Trees and Shrubs (Gillman et. al):

Newly planted plants require routine watering. Typically, 5-7 gallons, applied to the root ball once a week, is an appropriate quantity of water to add to a newly planted tree or shrub; however, differing soil and weather conditions will affect the frequency with which water must be added. Examine the soil moisture 4-8 inches deep to determine the need for water. If the soil feels dry or just slightly damp, watering is needed. Soil type and drainage must also be considered. Well-drained, sandy soil will need more water, and more often than a clay soil that may hold too much water. A slow trickle of the garden hose at the base of the plant for several hours or until the soil is thoroughly soaked is the best method. Short, frequent watering should be avoided as this does not promote deep root growth but rather, the development of a shallow root system that is vulnerable to several environmental stresses.

Be sure to consult this publication for additional information about planting trees.

Question from Anne in Apple Valley: On my 'William Baffin' roses, the leaves turned yellow with brown spots, then dropped. Bare canes are still green. Is this fungal and should I treat before winter? Should I prune the canes back to the a foot from the ground and clean up to try and avoid re infection next spring? These are large 7- yr old plants and don't want to lose them.

Answer: It sounds as though your rose has black spot. Here is a good publication Rose Diseases (Pfleger et. al). Black spot on rose is a fungal disease caused by splashing water onto leaves. We had a rainy spring and summer and thus this was a "good" year for such diseases. Note that sanitation is a good place to start in reducing the occurrence next year. Treatment occurs during the growing season when the first signs of the disease occur. It is not appropriate to treat now. Diseased canes should be cut back a few inches into healthy wood. You can also help reduce water droplets that can foster fungal spores by watering at the base of the plant and mulching the roots. Space out the canes as you tie them to your trellis / fence so air can circulate, drying off leaves and canes. 

Question: Should a Fat Albert spruce be fertilized now?

Answer: Stop fertilizing trees and shrubs in mid-summer. Fertilizing now will cause new growth to occur that can be damaged by cold temperatures. Water evergreens now up until you cannot water any longer. This will reduce the chance of desiccation and browning of needles. More on evergreens

Question: Can I prune the water shoots off my crab apple now? How often can we prune to preserve size and shape?

Answer: Crab apple trees should be pruned once a year in late winter while still dormant. This will reduce infestations by pests and all the plant to heal the cut wound more quickly when it begins actively growing in early spring. Remove water shoots and selectively prune branches to open up the canopy, allowing air and light to reach the inner branches and buds. Protect the tree from animal damage in the winter by surrounding the trunk with hardware cloth fencing or corrugated plastic tubing. More on pruning trees.

Question: How do I know when to re-pot a ZZ plant?

Answer: Zamioculcas zamiifolia or "ZZ plant" is not one of the plants I know well, I admit. After some reading, I found out it is a rainforest plant, but has about 3-4 months of dry conditions. The plant apparently does not do well when pot-bound / crowded; hence, it may stop developing new leaves and stems. That may be the indicator that it's time to re-pot. It is apparently an excellent houseplant that grows well indoors and has few if any pest issues. It may drop its leaves once a year and appear dead, but that is apparently just its dormant behavior. Soil should be well-drained. It does not need much fertilizer - either a slow release balanced fertilizer every three months or a very dilute liquid fertilizer (1/4 strength) when you water.

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.

Thanks for listening!

We aren't always able to answer everyone's text'd questions on the air, so we try to post a few along with answers here in the Yard & Garden News blog. Remember that you can always visit the U of M Extension Garden website for loads of gardening resources.

Hope you join us and our host Denny Long every Saturday, 8-9am, on WCCO Smart Gardens and happy gardening!

Question: It looks like my black-eyed Susans have powdery mildew. Will they be OK next 20140714_123750.jpgyear and what can I do?

Answer: Powdery mildew is a common fungus in Minnesota landscapes that results in a white powdery covering over leaves. Usually damage is cosmetic and the plant recovers fine the next year. The best means of managing this pest is to (1) select resistant plants, (2) space plants properly to ensure air circulation, (3) water at the base of the plant (vs. overhead watering) to minimize splashing spores onto leaves, and (4) clear away infected plant material. Fungicides are available, but usually not necessary and especially near the end of the growing season when plants are starting to dieback for the winter. More about powdery mildew ...

Question: My bee balm is done blooming. When can I cut back the dead blooms?

Answer: You should deadhead (cut off) spent blooms on perennials like bee balm (Monarda) throughout the growing season. This improves the look of the plant, reduces the plant energy going into producing seed, and also can prompt a second, though typically smaller, re-bloom. About pruning perennials

Question: When should you prune spireas?

Answer: When you prune a flowering shrub depends on whether the plant blooms in the spring (on old wood) or in summer (on new wood). If the plant blooms in the spring, it grows or "sets" flower buds for the next year within a few weeks of blooming, so it should be pruned within two weeks of flowering. If the plant blooms in the summer, flower buds are produced on the new spring growth, and it should be pruned in late fall or early spring before growth begins. More about pruning shrubs

Question: I have a row of crabapples I have diagnosed as having apple scab. Is this P1250030.JPGsomething I can treat myself or do I need a professional?

Answer: Like all gardening problems, a correct diagnosis is critical before deciding on any mode of action. Apple scab can be managed by a home gardener with fungicides. More about managing apple scab.

Looking forward, Minnesota gardeners can reduce pests (diseases, weeds and detrimental insects) by choosing resistant plant cultivars and varieties that are suitable to the conditions of your site (light, soil, hardiness zone, etc.). It's also critical to a healthy landscape to space plants according to their mature size to ensure better air circulation and light to reach the plants, and the plants to achieve their natural form. Mulch plants and water at the base pf the plant to avoid splashing soil-borne pathogens (fungi, bacterial, etc.) onto lower leaves. Properly pruning plants and cleaning up dead leaves and other plant debris from your garden will also help reduce pests that overwinter in these materials.

Question: Is it OK to fertilize evergreens in September and October?

Answer: Time to stop fertilizing plants as fertilizing will prompt new growth. Our plants start to move into dormancy as the weather changes, and any new growth can be killed by cold weather. That said, be sure to keep watering your evergreens - and other woody plants - throughout the fall to help reduce the possibility of dessication during the cold dry winter months. More about protecting trees from winter damage

Question: We have some "critteres" tunneling in our raised vegetable / flower beds and actually killing plants. What should we do?

Answer: Gardening with wildlife is always a challenge! Identify the animals first and try to determine how they entering your raised beds. You don't mention how your raised beds are constructed, so I am going to assume they are built in wood frames about 6-12 inches deep. Are the animals climbing into the beds? If so, hardware cloth fencing (very small wire grid) dug won below the surface and high enough to keep them out should help. Are they tunneling in through a hole or crack in your raised bed structure? If so, patch / plug the hole or crack. If they are entering from tunnels underground and if it's logistically possible, remove the soil, line the bed with hardware cloth, and put the soil back into the raised bed.

Repellents are also available, but often need to be reapplied and may not be available for the kinds of edibles you are growing.

Question: We recently lost two large birch trees in our landscaping near our house. We just had the stumps ground out. Can I replant another tree in that same spot?

Answer: Since you ground out the stump, then yes, you can replant. That said, before planting, try to figure out why the trees died - too close to the foundation, pest problems, poor soil, unsuitable conditions for the tree species - and try to correct the problem(s) before planting again. Paper birch do not do well in our urban conditions - compacted soil, heat, dry conditions, alkaline soil. Understand your soil and choose a new tree that will thrive in your soil, the amount of light and the space available (note the mature width of the canopy when you are looking at tree species). Then plant the tree correctly, provide adequate water and staking. More about planting trees.

Question: We are going to be over seeding our lawn due to bad winter damage. We live in sandy acidic soil . We have removed most of the moss. Can we seed and then lime?

Answer: Turfgrass species grow best in slightly acidic soil.  I would suggest having the soil tested to see what the pH is.  If the pH is below 6, then lime would be recommended to increase this slightly.  Turfgrasses grow best at a pH of 6.5.  You can lime anytime, either before or after seeding.  Basic soil tests are $17.00 from the University of Minnesota soil testing laboratory. If the pH is in fact low, there will be a recommendation on the soil test for how much lime to apply.  

Question: How do I get rid of creeping charlie?  

Answer: Creeping charlie can be an aggressive weed in many sites and has a particular competitive advantage over turfgrass in wet/shaded environments.  Herbicides used to control creeping charlie provide marginal success due to the waxy leaf surface that repels herbicide applications.  I suggest making an assessment of how much existing grass is in the lawn that you are trying to preserve.  If the lawn is 75% grasses, then I would suggest several applications of a selective broadleaf herbicide, which will control the creeping charlie and preserve the grass species.  The best herbicides for this include post emergent combination herbicides with the active ingredient tricolpyr. Sometimes these herbicides are labeled as clover or oxalis killers.  Fall is the best time to apply these herbicides, and multiple applications spaced 2-3 weeks apart would generally be required for any success.  The the lawn is predominately creeping charlie, the best option would be to control it with a complete vegetation killer like Roundup (glyphosate) or diquat.  till several applications will be required.  Following successful control of the existing vegetation, seed shade tolerant turfgrass species such as the fine fescues or tall fescues.  If significant wet shade is present, rough bluegrass (Poa trivialis) is a species that might give you better results. More information on creeping charlie control

Where to purchase grass seed

Question: My back yard has always had a lot of moss. I've tried raking it out and seeding with grass seed but can't seem to get rid of the moss. Is there a way to get rid of the moss?

Answer: Moss is generally an indication of a poor environment for growing turfgrass, which includes shaded, moist, and compacted sites.  General recommendations for controlling moss in lawn situations would include reducing the amount of shade (pruning), aerating to help with water infiltration, reducing irrigation frequency, increasing the mowing height, and planting shade tolerant grass species.  Moss takes over and establishes in lawns with poor stands of turf, but rarely competes with the turf itself.  I suggest aerating to reduce compaction and pruning to improve light penetration and air movement.  Follow this by seeding with shade tolerant grasses: moist to dry shade- fine fescues or tall fescue, wet shade- rough bluegrass.  Moss controls on the marketplace will only have marginal success.  Start with the cultural control options to improve the health of your grass, followed by seeding.  More on moss control

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