Nuisance insects appear in homes

By Katie Drewitz, University of Minnesota Extension 

Boxelder Bug

The warmer-than-usual temperatures this winter have led to a prolonged season of nuisance insects. These insects include cluster flies, boxelder bugs, sowbugs, multicolored Asian lady beetles and more. Fortunately, these insects are harmless, although annoying, especially when many of them are present. 

Below are a few things to keep in mind when dealing with nuisance insects.

First, it is important to know that these insects are not reproducing indoors. Due to the emergence from their hiding places periodically throughout the winter and early spring, it appears they are laying eggs and their offspring are emerging. In fact, all of the insects seen now entered the home last fall. They hibernate in balls or clusters in wall voids, attics, and similar areas. As the temperatures warm, the insects in the outer layers become active first and then emerge into the living quarters of the home, explaining why they do not all become active at the same time. This has been especially noticeable this winter. 

Since these insects are emerging from hidden sites, it is not practical to treat them to prevent their emergence. Once they are out in the open, the best way to deal with them is physical removal, such as vacuuming. Eventually, all these overwintering insects will become active and move away from their overwintering sites. 

To minimize these kinds of problems in the future, it is important to treat these insects in the fall as they are first trying to enter the home. 

This is a two-pronged approach. First it is important to inspect the outside of the home during summer and seal spaces and gaps that may be used by the insect to get inside. This can be followed up with an insecticide application in the fall, just as these insects are trying to get inside. This insecticide application is typically applied to the outer perimeter of the home. It is not possible to prevent all nuisance insects from entering into a home, but it can reduce the number, causing fewer headaches later during the winter and spring. 

With questions, reach out to your local Extension Educator. Residents in Fillmore and Houston counties can call 507-765-3896 or 507-725-5807. 

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