Boxelder Bugs in Delaware: How to Spot Them and Keep Them Out

What they look likeSignsAre they dangerous?How we treat themPreventionFAQ

What do they look like?

Boxelder bugs are about 1/2 inch long and brownish-black, with reddish-orange stripes behind the head and a red abdomen. They feed on boxelder trees, mostly female ones, and also on maple and ash. In fall they mass on sunny, south-facing walls and push into cracks to spend the winter. A warm wall covered in them is a giveaway.

Signs you have them

• Groups of black and red bugs on sunny, south-facing walls in fall
• Bugs crawling into cracks around windows and siding
• Bugs coming back out inside in late April and May
• Boxelder, maple, or ash trees nearby

Are they dangerous?

Boxelder bugs are a nuisance only. Penn State Extension says they cause no structural damage, and they don't reproduce indoors. The bugs you find inside came in from outside to spend the winter. Avoid treating them inside wall voids, because dead bugs there can draw carpet beetles.

When are they active?

They gather on houses in the fall and come back out in late April and May.

How Wolfe treats them

Sealing gaps works best, so that's where we start. If they're about to gather, we can apply a fall perimeter treatment just before they mass on the house. Penn State Extension notes it only lasts a few days to about a week, so timing matters. We don't treat wall voids, since dead bugs there draw carpet beetles. Call us at (302) 697-8969 to plan your fall visit.

How to keep them out

• Seal cracks around windows, doors, and siding.
• Vacuum up any that get inside.
• Don't spray into wall voids.

Common questions

Sources: Penn State Extension: Boxelder Bug

Last reviewed October 2026 by Wolfe Pest Control.