Quick Scoop: What are boxelder bugs?

Boxelder bugs are black-and-red insects that feed mainly on boxelder trees, and they often show up around homes in the fall as they look for warm places to overwinter. They’re mostly a nuisance rather than a dangerous pest, because they usually don’t damage houses and are not known for biting people.

What they look like

Boxelder bugs are typically flat, elongated, and black with red or orange markings on their wings and back. The adults are about half an inch long, and the younger nymphs are smaller and often bright red.

Why they appear indoors

In spring and summer, they live and feed outdoors on female boxelder trees and sometimes maple, ash, and a few fruit trees. When temperatures drop, they gather on sunny walls and slip into cracks, attics, basements, and other hiding spots to survive the winter.

Do they cause damage?

Their plant feeding can sometimes cause minor leaf discoloration or slight fruit deformities, but serious plant damage is uncommon. The bigger issue is the inconvenience of seeing lots of them near windows, walls, and inside houses.

How to handle them

• Seal cracks, repair screens, and close gaps around windows, doors, vents, and the attic before fall.

• Remove piles of leaves, boards, rocks, and other debris near the house where they hide.

• Vacuum or sweep up bugs indoors instead of crushing them, since crushing can leave stains and a bad odor.

• Wash them off walls or tree trunks with a strong stream of water when needed.

One-line takeaway

Boxelder bugs are harmless-looking but annoying fall invaders that gather near boxelder trees and sometimes end up in houses.

TL;DR

They’re red-and-black nuisance bugs tied to boxelder trees, they often come indoors in cool weather, and the best fix is sealing entry points rather than trying to spray them inside.