Boxelder Bug Biology

For some unfortunate homeowners boxelder bugs are a yearly ordeal. These relatively large but harmless bugs like to congregate on certain houses in the fall. They may even find ways to get indoors. The good news is they pose no real threat to you or your home and don't breed indoors. The bad news is they may be back next year, and the next. They can be a real nuisance when they congregate in large numbers around the house. If they get indoors they can soil interior furnishings with their droppings and they may stay all winter.

Unfortunately we don't have any permanent solutions to offer but there are a few things that will help. Caulk openings and cracks around doors and windows and repair window and soffit (roof vent) screens to block entry. If bugs get in, in large numbers, it may be necessary to treat wall voids and attic spaces with insecticide. See our DIY Boxelder Bug Control article for additional suggestions.

Why are certain houses selected by boxelder bugs?

While it is not entirely clear why some houses are selected, boxelder bugs seem to be attracted to those that share certain characteristics. Tall buildings, two-story or higher, get more attention from these critters. Also, houses that are sited high relative to their surroundings. They also favor houses with large trees immediately adjacent, especially if these trees are on the side that gets afternoon sun. These large trees seem to act as beacons when the adult bugs are on the move. During sunny afternoons bugs that are resting in the trees fly onto the warm housesiding.