As the weather is growing cooler, have you wondered what are those black and orange (or red), half-inch long bugs clinging in swarms to the sunny side of your house or door? Most likely, they are boxelder bugs. These bugs may not be noticeable in the summer when they live and feed in boxelder and maple trees. As the weather grows cold, however, they look for ways to get into your warm house.

Boxelder bugs belong to the same family as stink bugs, cicadas and insects with “piercing and sucking mouthparts.” They release a bad odor when crushed. They emerge, bright red, in the spring and feed on female boxelder trees; although they may also feed on maple or ash trees. 

Boxelder bugs are most prolific during hot, dry summers following warm springs. This year may have produced the right conditions for them to be quite plentiful. In the fall, the bugs look for cracks and spaces around doors and windows to sneak into your house. They are not generally harmful but they can be an annoyance.

Other than removing your female boxelder trees, the best way to manage boxelder bugs is to seal cracks and holes around windows, doors and foundations. If you have large invasions, you can treat the outside of your home with an insecticide treatment. The best time to spray is late summer and early fall. Once inside, your best option is to remove them with a vacuum or broom. Boxelder bugs do not live for more than a few days inside your home when they are active but they can be a nuisance, staining surfaces with their excrement. Some boxelder bugs remain inactive in your home over the winter. If you see them inside in the spring, they are waking up and trying to go outside.

References:

https://extension.umn.edu/nuisance-insects/boxelder-bugs

https://extension.colostate.edu/topic-areas/insects/boxelder-bugs-5-522/

Photo credits: University of Minnesota Extenison (1, 2), CooperPest (3)