Macomb County Pest Control

Wasp Removal

Overwintering Wasps/Yellow Jackets/Hornets

A homeowners guide to Wasps

Technically, Paper Wasps, Yellow Jackets and Hornets are Wasps.

These insects are cold blooded and are in the same biological family as ants. This is important to remember, as they will become more active as the temperature rises.

They are social insects that build aerial nests of a paper-like material called carton. Carton is a mixture of wood fibers and the salivary secretions of the female wasps. In Michigan, new colonies must be founded each year because the mated queens from the previous year’s colonies overwinter. Queens are inactive during the winter months, going into a diapausal stage (similar to hibernation). They hide in protected niches under tree bark, in stone walls, attics and other sheltered locations.

In early Spring, overwintering queens, called Foundresses, visit exposed wood surfaces (decks, siding, fences, dead tree limbs etc.) and chew away loose wood fibers. These wood fibers are then mixed with salivary secretions to form the paper like nests.

Seasonal weather patterns such as excessive moisture or dryness and harsh winters will affect the wasps population. This helps to explain the varying levels of nest building activity year to year.

It is important to know that wasps do not reuse their nests from one year to the next.

In the following blog, we will discuss wasp biology, wasp treatments, and wasp removal.

Paper Wasps (Polistes spp.)

Polistes build rather simple nests consisting of one tier or layer of cells. The cells open downward and are not covered. Collectively, this layer of egg cells is called a comb.

Nests are usually suspended beneath horizontal surfaces and commonly hang from eaves of houses, beneath window sills and porch roofs. They can be found in hollow poles or pipes as well.

Polistes nests are rather small, rarely over one foot in diameter and there are seldom more than 100-200 workers on the nest at any time.

Polistes are often found swarming in early spring and late fall. During the spring, the queens are searching for suitable nesting sites and in the fall, mated females release from their overwintering sites during warm afternoons. This random activity will diminish as the days grow colder.

Oftentimes we receive calls from homeowners that see random Polistes inside their home in late fall or early spring. Being cold blooded, when the temperature warms temporarily, the Polistes will begin to move around. This is only temporary and is no cause for concern.

Our advice is to remove them with a vacuum cleaner…as they will be lethargic and not very aggressive.

Yellow Jackets (Vespula spp.)

Yellow Jackets are considered to be the most dangerous of the social wasps because of their nesting habits and aggressive foraging behavior.

They are the smallest of the common Vespids. They are approximately ½”-3/4” long, have slender bodies and are yellow with black stripes. They are often mistaken for honey bees while in flight or foraging for food.

Unlike honeybees, when yellow jackets sting, they do not lose their stinger. Yellow jackets emit a pheromone when alerted which signals others in the area of a danger or threat. This helps to explain why people are often swarmed by stinging yellow jackets.

In addition to building aerial nests that are often attached beneath soffits or in trees, yellow jackets many times build nests in the ground. Found in voids in tree or shrub roots, vacated animal burrows or existing holes in the ground.

Homeowners are often attacked when walking close to the nest while cutting grass or doing related yard work.

If you discover a yellow jacket nest, our advice is to call a professional. Due to the fact that they are very aggressive, removing their nests should be left to a professional.

Bald Faced Hornets (D. maculata)

Bald Faced Hornets are easily recognizable. They are the largest wasp and their black body with white stripes and white markings between their eyes make them quite easy to recognize.

They are ¾-1” long. And like yellow jackets they build aerial nests primarily in trees. They are very territorial and will become very aggressive if they are threatened.

Their nests can become very large, oftentimes exceeding 18”. They are a grey paper-like material and resemble an inverted soccer ball.  They are enclosed unlike polistes nests and have an opening in the bottom that is used for entrance and egress to the nest. Their nest can contain upwards of 700 workers.

Practical Tips and Do’s and Dont’s

Once a nest has been located, the treatment will depend on a number of factors. Each situation is unique and requires a different approach.

Every year, homeowners (with good intentions) make several common mistakes when trying to eradicate a nest. If the nest is in a wall void DO NOT UNDER ANY CIRCIMSTANCES spray an aerosol in the entrance hole. That nest will not be affected by the spray and there is a great chance the wasps will begin to enter the house via duct works or other interior gaps.

This type of nest requires a specific treatment that homeowners are not equipped to deal with.

The second remedy homeowners often attempt (again with good intentions) is to SEAL THE ENTRANCE HOLE. Depending on the time of the year, doing so will result in hundreds if not thousands of wasps entering your home. Once the hole is sealed you have removed the wasps ability to enter (and exit).

In late summer, homeowners often hear a buzzing sound behind the walls. This is indicative that the nest is directly behind the wall. Again, there are some Do’s and Don’ts with this scenario.

DO NOT pound on the wall. Very often, the only thing between you and the nest is the paper and paint on the drywall. We’ve had many instances where homeowners have put their fist directly into the nest resulting in serious injury. DO CALL A PROFESSIONAL!

Also, in late fall homeowners can experience a ‘break through’. Occasionally nests will become so large that they will ‘break thru’ the drywall in your home. This usually occurs in a corner or where the drywall meets at a 90 degree angle.

This is definitely time to call in the pro’s. It is a complicated treatment and not one a homeowner can tackle without the proper equipment.

For more information, or to schedule an appointment, please contact “Environmental Systems Pest Control” @ (586) 731-2120


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