If you are seeing black and red bugs scurrying about near trees and buildings, they may be boxelder bugs. Boxelder bugs (Boisea rubrolineata) feed on the flowers, leaves and seedpods of female boxelder trees (Acer negundo) and occasionally are found on maple and ash, and sometimes on certain stone fruits and grapes.

Boxelder bugs are often confused with other insects that look similar such as red-shouldered bugs, squash bugs, the bordered plant bug, and leaffooted bugs.

This insect doesn't usually cause significant damage to landscape plants, but when their numbers are high during fall, they can build up on outside walls or sometimes enter houses and may be considered a nuisance.

If you have a...

The western boxelder bug (Boisea rubrolineata) usually feed on the leaves, flowers, and seedpods of the female or seedbearingbox elder tree and occasionally occur on mapleand ash trees. They sometimes feed on certain stone fruits and on grapes, where their feeding punctures cause the fruit to become deformed. Large numbers of the bug usually occur only on female box elder trees.

While boxelder bugs do not cause significant damage to landscape plants, but they may become a nuisance by invading homes in the fall in California. If boxelder bugs become a problem, seal up entry points such as cracks and screen windows and doors, and eliminate hiding places and debris outdoors.

Boxelder bugs are sometimes confused with other...