We have experienced several periods this winter of above-average temperatures. If you've been outside, you may have noticed that these warm days have led to increased insect activity. You might have even noticed more insect activity inside your home.
Boxelder bugs are one species of insect that likes to make an appearance on warm winter days. They can be found both inside and outside of your home, especially as seasonal weather changes.
Adult boxelder bugs are fairly easy to identify. They have black to gray bodies with red to orange stripes on their backs. Their eyes are red and they are about ½-inch long. Nymphs, or the smaller stage of boxelder bugs, are bright red with dark heads.
Boxelder bugs feed on the seeds and sap of boxelder and maple trees, but may also feed on apple, ash, plum, cherry, and grape plants. They usually don't cause enough feeding damage to severely harm their host plants.
They are known to most people as household pests. At the end of summer and into fall, boxelder bugs congregate on boxelder trees and search out a suitable spot to hide out for the winter. They prefer to hide in cracks and crevices, which can be on trees or those in our homes.
Boxelder bugs can find their way into the smallest crevices around windows and doors, as well as gaps between your roof and attic. The bugs will overwinter behind walls, beneath baseboards and in the attic. As temperatures rise going into spring adults emerge from their hiding places and attempt to make their way back outside.
Boxelder bugs are in no way harmful to humans. They don't bite or sting. It is usually not warranted to apply a pesticide in order to control them. If you kill the adults emerging in spring, this won't do any good in keeping bugs from coming in next fall, since they will be of a different generation.
If you see boxelder bugs in your home, the best control method is to sweep or vacuum them up. You will be much better rewarded by concentrating your efforts on preventing bugs from entering your house by fall.
Caulking and weatherstipping around doors and windows will seal off gaps insects use for entry. Make sure all of your windows have screens and replace any broken screens. Vents and soffits with openings to the attic or crawl spaces should be screened off.
Boxelder bugs will often gather in great numbers on your house siding in the fall. Spraying them with an insecticide at this time will prevent some of them from entering your house.
Identification and removal of nearby boxelder trees can also help eliminate the biggest source of boxelder bugs.