The boxelder bug is about 1/2 inch long, black, with three red lines on the back and red lines along the sides and wings. The wings lie flat on the back when at rest. The immature stages have red abdomens. Boxelder bugs feed on the leaves, flowers, and seeds of boxelder and other maple trees. These bugs cause little damage to trees and do not bite.
Adult box elder bugs lay eggs in the spring and the nymphs emerge in a few days. Nymphs develop into adults during the summer, which then mate and lay eggs that hatch into the nymphs of the second generation. In the fall, adults gather on the south side of buildings to spend the winter. They may move a long distance from their host tree to an over-wintering site. Adult bugs enter buildings where they hide in small cracks and crevices in walls, door and window casings, and attics. During winter and early spring, they come out and move about the house.