Ana Heck and Nate Walton, Michigan State University Extension - October 24, 2023
Updated from an original article written by Howard Russell. Garage Door Opener Spring Cost
How to deal with wasp nests and decide when they need to be removed.
Killing off a wasp nest is tricky business. As many of us know, wasps can be quick to sting people who approach their nest. This article will help you decide if you need to remove a wasp nest and provide you with options if it must be removed.
Many species of wasps provide beneficial ecosystem services such as feeding on garden pests. Wasp nests that don’t pose an immediate hazard can be left alone. Wasps vacate their nest in the fall and don't reuse the same nest the next year. After a couple of hard frosts, the wasps should no longer pose an issue. Leaving wasp nests alone may reduce insecticides in the environment and support beneficial insects.
Professional pest removal companies can remove wasp nests that pose a threat to humans, pets or livestock. Anyone who attempts to use insecticides for wasp nest removals should follow the pesticide’s label and take precautions to avoid stings or other injuries.
Many species of wasps, bees and even flies can look alike to the untrained eye. Begin by confirming that you are dealing with social wasps by reviewing insects that look like bees from Michigan State University Extension (MSU Extension). Michigan residents can submit photos of the insect or its nest through MSU Extension’s Ask Extension form for help confirming they have wasps. If you discover you’re dealing with honey bees, consult “What should I do if I find a swarm of bees?" by MSU Extension for clusters of honey bees that are exposed, and consult Michigan Beekeepers Association’s cutout list for honey bee colonies that need to be removed from structures.
The wasps that may become a nuisance in late summer and fall belong to the family Vespidae. Though many species of vespids lead a solitary lifestyle and rarely cause us problems, yellow jackets, bald-faced hornets and paper wasps are social insects that live in large colonies. They construct their nests in the ground, in trees, under eaves and inside wall voids and attics. Nest construction starts in late spring and continues throughout the summer. The last brood raised includes males and next year’s queens. Due to the importance of these reproductives, the worker wasps become very protective and defensive toward those who venture too close to the nest this time of year.
In northern latitudes such as Michigan, social vespid nests are abandoned in the fall. After the new queens leave, all the workers eventually die due to starvation and cold weather. After mating, the queens seek protected sites in which to spend the winter; they are the only ones that survive the winter. The following spring, the queens emerge and search for a suitable nesting site and begin constructing new nests. Old nests are never reused, but a favorable nesting site may be selected year after year.
During August, the colony reaches its maximum size of worker wasps. The maximum size depends on the species; paper wasps may only produce a few dozen workers, while colonies of yellow jackets may reach one or 2,000 wasps.
An important consideration when contemplating whether to eliminate a wasp nest is its location. Nests located in out-of-the-way sites that are not likely to be disturbed can be ignored since they are going to die out later in the year. Small, exposed paper wasp nests can be controlled by aerosol wasp sprays that produce a concentrated stream of insecticide that has a range of 15 to 20 feet or with a hose on the jet setting. Paper wasps do not cover their nests in a papier-mâché envelope like those of yellow jackets and bald-faced hornets, so their brood cells and workers are exposed and vulnerable. Read and follow the pesticide’s label, point the nozzle at the nest, and spray the pesticide on the nest.
The larger nests of yellow jackets and bald-faced hornets that are protected by a paper-like envelope are more challenging and best left to pest control professionals. If you spot an aerial nest in the fall and the wasps are in a low-traffic area, wait until after the first freeze to remove the nest.
Ground-nesting yellow jackets are often discovered, sometimes painfully, while mowing the lawn or weeding gardens and flower beds. Vibrations from lawn equipment irritate the wasps and stimulate a defensive response. Inspecting your yard for yellow jacket nests before mowing or undertaking other yard maintenance activities can prevent an unfortunate surprise encounter. If you identify a nest opening where yellow jackets are active, approach it with caution. If possible, warn family and visitors to avoid the area until the colony ends its life naturally in the fall/winter.
In instances where the nest must be removed, ground nests are easily controlled with a single application of an insecticidal dust directed at the nest opening. Insecticidal dusts work well in these cases because the wasps pick the dust up as they enter the nest and carry it to the core of the nest. This insecticide contaminates the entire nest and soon all the wasps will die off, normally within one or two days. Early morning is the preferred treatment time and the precautionary measures outlined in the above paragraph should be followed. Apply an insecticidal dust with a disposable paper cup or bulb duster. Then, quickly dump the cup or bulb duster directly in the nest opening and move away from the nest with great haste.
If this application is done correctly, white, dust-covered wasps will quickly issue from the opening and fly off to meet their fate. Don’t cover the opening with soil or a rock; leave it open so the wasps can enter and leave as they please. Dispose of the paper cup or bulb duster according to instructions on the pesticide’s label.
As mentioned earlier, yellow jacket wasp queens search for nesting locations in the spring in Michigan. They do not dig their own holes. Instead, they take over burrows that have been abandoned by rodents, such as chipmunks that have nested in your yard. You can prevent yellow jackets from making a home in your yard by inspecting periodically for rodent burrows and filling them in during the spring and early summer.
The most challenging of all social vespids to get rid of are those that construct concealed nests inside walls, attics and other areas inside homes and structures. Wasp sprays are seldom effective against these nests because the nest is often located some distance from the entrance and the spray never reaches the core of the nest.
If you discover yellow jackets nesting inside your home, you can choose to ignore it or call a pest control company to destroy it. Do not plug the outside opening of these nests because this will force the wasps to chew their way into the interior of the house, and this is never a good thing. Pesticides applied in these situations must name buildings or structures as allowable application sites on their labels.
Be sure to read and follow all instructions and safety precautions found on the label before using any pesticide.
This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).
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