The Tiny Red & Black Flying Bugs in the House

Behavior

• Boxelder bugs appear in the spring and feed on plant materials. After they mate, they look for female boxelder trees and lay their eggs on the trunks, branches and leaves. Boxelder bugs also sometimes lay their eggs on maple or ash trees. In the fall, these bugs look for places where they can overwinter. They fly up to two miles away from their feeding sites to find overwintering sites. Boxelder bugs may enter your house at this time.

Problem

• Boxelder bugs don't damage plants or building structures, but they become a nuisance when they gather inside the house from autumn to spring. They may bite if you touch them and their excrement may stain various surfaces inside the house. You may see boxelder bugs around windows and other sunny areas around the house. They become inactive and hide in the attic or behind the walls when it gets cold, then emerge again the next spring. They usually leave the house in the spring, but may not be able to find an exit and become trapped inside.

Indoor Control

• If boxelder bugs are already inside the house, you can't simply treat the house with an insecticide to kill them all because they hide in various inaccessible areas around the house. Whenever you see boxelder bugs in the house, use a vacuum cleaner to remove them. If you crush a boxelder bug, it may release a substance that can stain surfaces. Insecticidal aerosol sprays and household cleaners may kill them, but the chemical has to come in direct contact with the insects.

Outdoor Control

• Removing all the female boxelder trees in the vicinity may stop boxelder bugs from entering your house next year. However, this may not be possible. If boxelder bugs have not entered the house, you may see them clustering on the sides of the house. Spraying these areas with a residual insecticide may reduce the number of boxelder bugs that enter the house. Sealing all gaps in the building exterior also keeps them outside.