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Extension > Yard and Garden News > Inspect for wasp nests

Thursday, June 23, 2016

Inspect for wasp nests

Jeffrey Hahn, Extension Entomologist

Now is a good time to inspect your home for wasp nests that are being constructed. It is easy to overlook nests when they are small and there are only a few wasps present. However, that is the best time to treat them when you can find them. Some wasp nests are built out in the open, e.g. under an eaves, and are the easiest to find and control.
A wasp (yellowjacket) queen constructing her nest during
June. The nest and queen were removed in a container and
the queen was later released to nest else where.
Photo: Jeff Hahn, UMN Extension

If a small, exposed nest is discovered, there are a couple of options for controlling it. Regardless of which method you use, deal with nests at night when the wasps are not very active. The easiest method is to spray a wasp and hornet insecticide into the nest to kill all of its inhabitants. If you want to control it nonchemically, remove the nest by placing a clear glass or plastic container over it and moving the jar so the nest is knocked down into the container. Slide a piece of cardboard (or something similar) so you can bring the jar down without the wasps getting out. Then slide the lid on the jar. Either release them so they can build a nest somewhere else or place them in a freezer to kill them.

Nests that are hidden, such that you can see wasps flying in and out of a space, but the nest in not seen, are more challenging to find because there are not as many wasps flying back and forth to give away the location of their home. These nests are typically not discovered until late summer when larger numbers of wasps are present. Control of these nests is more challenging because spraying into the opening rarely gets into the nest to kill the wasps. An insecticidal dust is the best option. However dusts labelled for buildings are not commonly available to residents and are often difficult to find. The best option then is to contact a pest management service to treat the nest.

A European paper wasp nesting in a bird feeder. This nest
and the wasps was removed in a jar and removed from the
property.  Photo: Jeff Hahn, UMN Extension
The nests of European paper wasps are particularly interesting because they will nest in such a wide variety of sites. They can be found exposed on horizontal and vertical surfaces as well as in all kinds of cavities. They can be found in the most unexpected places, like in bird feeders. Deal with them as you would other wasps.

For more information about wasps, see Social Wasps and Bees in the Upper Midwest.




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