Jeffrey Hahn, Asst. UMN Extension Entomologist
Some insects, particularly boxelder bugs, multicolored Asian lady beetles, cluster flies, and hackberry psyllids, will fly to buildings and congregate on the outside, especially on the south and west facing exposures where it is the sunniest. As they find spaces and cracks to get inside, some end up in attics, wall voids, and other spaces (where they remain until a mild winter day or spring) while others find their way into the interior part of homes. Yet other arthropods, such as sowbugs, millipedes, and crickets, don't fly but crawl to buildings and find their way indoors at ground level.
Regardless of which nuisance invader you find in your home, the good news is that they do not reproduce indoors and are essentially harmless to people and property. They are short-lived indoors, although some, like boxelder bugs and multicolored Asian lady beetles, can successfully overwinter and can move into the inside of homes periodically during mild winter days and in spring.The best management of nuisance invaders is prevention; take steps to keep these insects and arthropods out of your home to begin with. First, examine the outside of your home for possible entry points that they may use to enter your home. Look particularly around windows, doors, where utility lines enter buildings, and areas of buildings where vertical and horizontal surfaces meet. If you are dealing with flying insects, concentrate your efforts on the south and west facing exposures. If you are dealing with crawling insects, check for mulch, leaves, and other possible debris close to the building that may provide harborage. Removing this will make it more challenging for them to get inside. It isn't possible to insect-proof your home so that nothing can get in, but it is possible to minimize the number of insects and other arthropods that can into your home.
Once insects and other arthropods get inside, you do not have many options other than to physically remove them with a vacuum or broom and dust pan.