Many pests fall under the heading of “fall invaders”. Of course, mice are the most notorious, but many common insects hatch heavily in the fall and must find protected areas to survive the winter as an adult. Examples in the Midwest include ladybird beetles, cluster flies, squash bugs, stink bugs, boxelder bugs, and paper wasps.
Country farmhouses and larger buildings often experience the most trouble. Even hospitals often have problems on the top floors. These pests seem to be cyclical in their numbers. Some years one species is much more problematic than others. Large fall hatches also vary with geographic areas. As these insects need heat to survive the winter cold, they have sensory organs that make them very good at detecting heat loss from structures. Heat rises so most heat loss occurs around rooflines and eves. Loose-fitting windows and doors are also common entry points. These insects fly and crawl to those heat sources and come right in. Common overwintering locations include attics, wall and ceiling voids, chimneys, etc. They can then come inside through light fixtures and cracks in walls and ceilings.
They often occur inside in the largest numbers when a spell of warm winter weather occurs. At that point, the best control inside is a vacuum cleaner with a crevice attachment. Insect light traps (ILT’S) positioned in attics and drop ceilings can be very helpful at this time. Of course, the best way to control/prevent this pest problem is to keep them from getting in at all. The most effective way to accomplish this is with exterior caulking and weatherproofing. It helps prevent heat loss and seals the bugs out. Often the most practical measure is the outside application of a residual insecticide, in September or October, to kill these pests as they enter.