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Where Did Those Annoying Insects Come From?

Jeffrey Hahn, Asst. UMN Extension Entomologist

Photo 1: Boxelder bug.
Jeff Hahn .

It is common during mild winter weather to see various nuisance insects in your home, especially boxelder bugs, multicolored Asian lady beetles, and western conifer seed bugs. Despite the appearance that they have laid eggs and are hatching now, these insects have actually been in homes since fall when they first entered structures.

When they came into buildings in the fall, some insects accidentally moved all the way into homes. Others took refuge in wall voids, attics, and other nooks and crannies. As long as these areas stayed cold, they remained inactive. However, when it became warm, they 'woke up' and moved towards warmth which would be the inside of your home. As we get closer to spring, we see this occurring more frequently. These insects often congregate together in clusters in these harborages so as these areas warm up, not all of the insects become active at the same time. Or they just could occur in places in the home that warm up at different times. The end result is that there will be insects emerging up at different times during the winter.

When you see these insects now, your options are limited. Your best bet is to physically remove them, e.g. with a vacuum. Insecticides are generally not suggested as it will not prevent the insects from emerging and you have to physically remove them whether they are dead or alive. If this is a problem you deal with every year, be sure to target control in the fall before the insects start moving inside. The best tactics are sealing as many obvious spaces that you can find and supplementing that with an insecticide treatment. Once these insects are in your home, there is little you can do.
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