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Extension > Yard and Garden News > May 2013

Friday, May 31, 2013

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.

Wednesday, May 15, 2013

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.

Thursday, May 9, 2013

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.

Rabbit Damage Revealed on Trees and Shrubs

M.Grabowski, UMN Extension

Photo 1: Rose bush with extensive rabbit damage

As gardeners inspect their landscapes this spring, many trees and shrubs have been found with extensive rabbit damage. Rabbits are one of the most commonly seen mammals in the urban environment. In Minnesota, our most common rabbit is the Eastern cottontail, Sylvilagus floridans.

Rabbits will spend much of their time eating grasses and other herbs but they will also chew on the bark of trees and shrubs and eat the buds of shrubs in the winter and spring. If left unprotected, rabbits will sometimes eat the bark from around the base of a tree or shrub. This is called "girdling" and can kill the plant.

Read Rabbits and Trees and Shrubs by wildlife expert Jennifer Menken of the Bell Museum to learn more about protecting landscape plants from rabbit damage.

Tuesday, May 7, 2013

Snow Molds Blight Minnesota Lawns - For Now

M. Grabowski, UMN Extension

Photo 1: Pink and gray snow mold on a Minnesota lawn

Michelle Grabowski, UMN Extension Educator

Persistent cold weather and late snow fall mixed with freezing rain have created ideal conditions for the growth of snow molds this year. Snow molds are caused by fungal pathogens that thrive in cold temperatures (just above freezing to about 60F) and high humidity.

M.Grabowski, UMN Extension

Photo 2: Small round patch of pink snow mold with a light center and dark border

Two types of snow mold are common in Minnesota. Pink snow mold, caused by the fungus Microdochium nivale, results in round dead patches in lawns that can be an inch or two across or as large as a dinner plate. These dead patches are often pale tan in color, matted down and may have a dark brown border. In sunlight pink snow mold patches turn pink to salmon colored as the fungus produces spores of these colors.

M.Grabowski, UMN Extension

Photo 3: Pink matted grass in a pink snow mold patch

Gray snow mold, caused by several species of Typhula, also cause pale gray to tan patches of matted down brittle grass that can spread up to 3 feet across. If the matted down grass of gray snow mold is examined closely, gardeners can see small black dots, about the size of a pen tip. These black dots are sclerotia, resting structures produced by the fungus that allow it to survive through harsh conditions. It is not uncommon to find both pink and gray snow mold in the same lawn.

M.Grabowski, UMN Extension

Photo 3: Large irregular matted patch of gray snow mold

M.Grabowski, UMN Extension

Photo 5: Small black sclerotia of gray snow mold

The good news is that although snow molds thrive in cold wet conditions, they go dormant as the weather becomes warm and dry. In many cases the snow mold fungi blight the grass leaves but do not kill the crown. In these situations, the grass will recover as the fungal pathogen goes dormant. In severe cases of snow mold, the grass plant may die and gardeners will need to reseed the infected area.

For now there are a few things that gardeners can do to speed the fungal pathogen into dormancy. Remove or spread out any remaining snow piles, so the snow melts quickly and the grass below is exposed to sun and air. Rake the lawn to remove any leaf debris and to fluff up matted down patches of turf. This will help improve air movement around the grass plants so leaves dry quickly after dew or rain. A light application of fertilizer in the infected patch can help grass recover. If no recovery is seen, reseed the area, taking care to rake away matted down grass so that seed has good contact with the soil below. Fungicides are not effective in controlling snow mold once the disease is established and should not be used at this time of year.

Monday, May 6, 2013

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.  

Strawberry Growers take Note!

Karl Foord - Extension Educator, Horticulture

Removing straw mulch on strawberries using lilac buds as an indicator

Sometimes nature is a better indicator of the best time to take action than our measuring equipment. Researchers Terry Nennich and Dave Wildung attempted to determine the best time to remove the straw mulch on strawberries using growing degree days (GDD) which are a measure of heat accumulation. GDD are often used to predict when a plant might flower, or how developed a pest might be to optimize the timing of control.

Karl Foord

Photo 1: Buds of Common Lilac (Syringa vulgaris)

In this case Terry and Dave found complications that made GDD a less reliable indicator for the timing of mulch removal. Given this they looked for other signs in nature that might be more useful. Their conclusion was that when the lilac buds open, it is time to take off the straw. This correlated well with the end of strawberry dormancy. Timing is critical as a delay in removal was shown to reduce both the total yield and the size of berries. The longer the delay the greater the loss in yield.

To this end please observe the pictures of bud break in common lilac (Syringa vulgaris) in photo 1 and in dwarf Korean lilac (Syringa meyeri 'Palibin' in photo2. Both taken May 6, 2013 in Chaska, MN.

Karl Foord

Photo 2: Buds of Korean Lilac (Syringa meyeri 'Palibin')

Is it time to remove the straw mulch from your strawberries? What is the status of the lilac buds in your neighborhood?

Wednesday, May 1, 2013

May 1, 2013 Issue

In this month's issue:

Spring Flowering Bulbs

What a difference a year makes

Fascinating Fragrances - Three Perspectives

Veggies for Your Patio

Wasp Queen in Homes in Early Spring

Extension Publications: New & Revised

Spring Flowering Bulbs

Karl Foord - Extension Educator, Horticulture

The recent snowfall and lower than normal temperatures should not harm the flowers derived from spring flowering bulbs. Low temperatures above 28 F and day temperatures in the 30s and 40s will not harm these cold tolerant frost tolerant plants.

However, if the temperatures drop into the low 20s or high teens, these plants can be injured.

Enjoy these hints of spring.

What a difference a year makes

Karl Foord - Extension Educator, Horticulture

Karl Foord

Photo 1: Autumn Blaze Maple 3 29 2012

Minnesota definitely offers us weather variability. And although we may remember last year's early spring it is often difficult to compare a memory with a memory in the making. To this I offer the following two photographs of buds from the same 'Autumn Blaze' maple tree (Acer freemanii 'Jeffersred'). The picture to the left was taken last year on March 29th. As you can see the samaras with whirligig characteristics permitting the seeds to move away from the parent tree have already started to form.

Contrast this with the picture to the right taken this year on April 30th. The bud is just beginning to break and this picture was taken a month later than the previous. And snow is predicted for tomorrow in many parts of the state. Mercy.

Karl Foord

Photo 2: Autumn Blaze Maple 4 30 2013

Veggies for Your Patio

By Mary Meyer, Extension horticulturist

P1070964.JPGAlmost anyone can grow a few vegetables or herbs in the summer, even if you do not have space or time for a traditional garden. You do need sun, however and a container that can be placed where you can easily water and harvest the plants. The easiest plants to grow are greens, such as lettuce, spinach, swiss chard, pak choy or bok choy and herbs such as basil, chives, thyme and rosemary. Use a container that drains well, holds enough soil so you do not have to water more than once a day in the summer, and will be big enough for the plants you choose.

Here are some ideas: an 8 inch pot holds about 1 gallon and can grow 2-3 lettuce, spinach or Swiss chard plants or 1 herb; a 10 inch pot holds closer to 2 gallons and can grow 2 pepper plants or 1 small tomato plant, such as Tiny Tim, Pixie, Hybrid Patio, all smaller tomato plants that are good for containers. Cherry tomatoes such as Sweet 100 or Sweet Million are large plants and need large containers, 3 gallon or more.
Use a lightweight potting soil and water regularly, fertilize with a slow release in the potting soil or add liquid fertilizer weekly when you water. Look for vegetables already potted for you at the garden centers this spring. Vegetables are popular and easy to grow, especially if you have full sun.

Fascinating Fragrances - Three Perspectives

Karl Foord - Extension Educator, Horticulture

If someone hands you a flower, what is the first thing you do? Smell it, of course. How often have you exercised this ingrain behavior only to come up empty?

My colleague and a contributing writer to this blog, Robin Trott sells cut flowers for a living and reports, "I feel cheated when beautiful flowers lack fragrance. I insist on having fragrant flowers in the bouquets I sell. To provide fragrance, we use herbs such as basil, lavender, mint, dill, and cilantro as fillers, and grow stock (Matthiola spp.) fragrant snapdragons (Antirrhinum spp.), Sweet Williams (Dianthus barbatus) and fragrant oriental lilies (Lilium spp.)".

The Human Perspective

Fragrances have been a part of human culture for a long time. The mere presence of flowers has been shown to have positive effects on human emotions, and recent research has shown that fragrant flowers are a "positive emotion inducer". This should come as no surprise to most gardeners.

Breeding improvements in flowers have rarely included fragrance characteristics, which were considered to have a negative effect on vase life. Recent studies on fragrance suggest that this might not be the case, and researchers at David Austin Roses are making progress in improving the vase life of fragrant roses. I find it quite encouraging that researchers are working to strengthen a plant characteristic that positively effects a person's overall enjoyment of a flower.

As an avid gardener, fragrant plants are a significant addition to my landscape. Killing four-lined plant bugs or weeding in my mint patch becomes much less of a pain when accompanied by the scent of mint. Sitting on the deck when the Wisteria is in bloom is a sensory gift. Fortunately, there are quite a few plants that offer the reward of fragrance.

The Plant's Perspective

Fragrance provides a vital service for the plant. A plant's distinct aroma attracts pollinators, thereby facilitating cross-pollination and the continuation of the species. The relationship that exists between the plant and the pollinator is one of intimacy and endurance. To experience the optimal range of plant fragrances, it is important to understand the plant's pollination strategy. For example, plants pollinated by moths produce optimum fragrance in the evening as moths are nocturnal. Thus Nicotiana is more fragrant at night, when its moth pollinators are out and about. Plants pollinated by bees produce optimum fragrance during the day as bees are diurnal. Thus snapdragons are more fragrant during the day, when its bee pollinators are likely to be active.

Different but specific fragrances also help to ensure that insects visit flowers of a similar species, increasing the potential for successful cross-pollination. From a long distance, flower fragrances are more effective than visual signals in attracting a pollinator, especially to small or hidden flowers. Flower fragrances tend to be at their highs when they have sufficient nutrition.

In addition, moderate to warm temperatures and high light tend to increase fragrances. For instance, roses are picked at night when they are at their most fragrant, whereas jasmine flowers are harvested when their fragrance is at its peak just before dawn.
Every plant has its own signature scent, a complex mixture of so-called volatile organic compounds that easily turn to gases and waft through the air. Some 1,700 different compounds from 990 different plants have been identified in flower fragrances so far, according to Natalia Dudareva, a Purdue University biologist whose specialty is floral scents.

To extend your garden fragrance window, why not grow the nectar plants that pollinators on the night shift prefer. Good candidates for moths include native night bloomers such as evening primroses, yuccas, phlox, sacred datura and evening snow. To attract giant silk moths, grow the host plants of their caterpillars. Oak, sassafras, maple, birch, ash, willow and cherry are a few favored larval plants.

The Insect's Perspective

Honey bees (Apis mellifera) have 170 odorant receptors, the researchers found, compared with 62 in fruit flies (Drosophila melanogaster) and 79 in mosquitoes (Anopheles gramblae). The enhanced number of odorant receptors underlies the honey bee's remarkable olfactory abilities, including perception of pheromones, kin recognition signals, and social communication within the hive. Honey bees also use odor recognition for finding food. University of Illinois Entomology professor, Hugh Robertson, who has conducted research on the honeybee genome, states: "Foraging worker bees might encounter a bewildering number of flowers to choose from, but they can discriminate between them using subtle olfactory cues," He goes on to say that "A large number of odorant receptors allows the bees to find food and communicate its location to other bees." In striking contrast, the researchers found only 10 gustatory receptors in A. mellifera, compared with 68 in D. melanogaster and 76 in A. gramblae. Clearly taste is more important to fruit flies and mosquitoes than it is for bees.

Our olfactory apparatus

The human sense of smell is carried out by two small odor-detecting patches. Each patch is slightly less than ½ of a square inch and contains some 2.5 to 3 million receptor cells (photo 2). For comparison, a dog has 220 million of these olfactory receptors (photo 3). Nonetheless, humans can distinguish more than 10,000 different smells and are capable to detect certain substances in dilutions of less than one part in several billion parts of air.

Extend your garden's fragrance window

Grow the nectar plants that pollinators on the night shift prefer. Good candidates for moths include:

  • Night Gladiolus: (Gladiolus tristis) has creamy yellow blossoms that have an intense spicy fragrance at night.
  • Pinks: (Dianthus plumarius) The pale pink flowers have a rich clove scent.
  • Evening Primrose: (Oenothera) With sweetly-scented blossoms of soft white, pink and bright yellow that open in the evening.
  • Moonflowers: (Ipomoea alba) This night-blooming relative of the morning glory perfumes the garden as its large 5 to 6 inch white flowers open at dusk. A quick growing climber with large heart-shaped leaves.
  • Evening Stock: (Matthiola incana) Small pink or purplish flowers are not showy, but emit an intoxicating fragrance at night. Grows to one foot with lance-shaped leaves.
  • Four O'Clocks: (Mirabilis jalapa) Sweetly fragrant and colorful trumpet-shaped flowers, open in late afternoon releasing a jasmine-like perfume. Found in the gardens of Thomas Jefferson at Monticello, the bushy plants grow 24 inches tall and are an annual in our climate.
  • Daylilies: there are many daylilies that bloom at night including 'Moon Frolic' and 'Toltec Sundial'.

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.
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