The Boxelder Bug (Boisea trivittatus) belong to a class of insects known as the true Bug. The saying goes that not all insects are bugs, but all bugs are insects. Although this Bug is only particularly damaging to Boxelder trees it can become an indoor pest in the autumn time.
The adult Boxelder Bug is about one-half inch long has a black body with red margins. Nymphs, immature insects, are smaller and completely red in color.
The species can be found throughout the Eastern United States up to the Rocky mountains and North to Canada. Although they can travel up to two miles during any given year they are usually associated with Boxelder trees and somewhat with Maple trees too.
During the spring and summer the Boxelder Bug can be found in smaller numbers usually on maple and boxelder trees. Most of the year they go largely unnoticed. In late summer and into fall they congregate on mostly female, seed-bearing trees. This seams to be their preferred place to mate and deposit their eggs prior to hibernation. Populations then are attracted to warm sunny locations as the Autumn season brings cooler weather. They are often attracted in large numbers to brick buildings with sunny exposures as the daytime sun radiates heat into the evening. This usually attracts alot of attention as they find their way into homes though siding, window trim, dryer vents, or other openings.
Boxelder Bugs are usually not that damaging. However their populations can escalate to very high numbers quickly and can induce some harm to stressed trees. This insect can be more of a nuisance pest as they find ways to migrate into homes as outside temperatures drop.
Many times prevention is the best treatment by making sure homes are sealed properly so these insects, or others, don’t invade the indoors. If a spray is necessary Insecticidal soaps and dormant oils are fairly effective. These are most effective when sprayed on building populations found on Boxelder trees in late summer through early autumn.
For a pdf copy of this factsheet: Boxelder Bug