Home / Pest Library / Boxelder Bugs
Boxelder Bugs in Delaware
Black-and-red bugs that cluster on sunny walls in fall and wander indoors.
| Peak season | Oct; Apr |
|---|---|
| Size | About 1/2 inch |
| Risk | Nuisance — no bites; crushed bugs may stain fabric |
How to identify them
Adults are oval, about 1/2 inch long, dull black with red or orange markings along the edges of the wings. The young (nymphs) are bright red and wingless.
Boxelder Bugs in Delaware
Delaware agencies don’t publish a boxelder bug fact sheet, so this page relies on Maryland, Penn State, Purdue and Cornell extension guidance. Boxelder bugs feed on the seeds of boxelder trees and other maples. In fall — usually October in nearby central Maryland — they gather on the sunny, south-facing sides of buildings, then hide in wall voids and attics for the winter. They become active again on warm winter days and in early spring.
When they’re active
Swipe to see all 12 months →
What you can do now
- Caulk around windows and add weather stripping around doors before fall.
- Vacuum bugs that get inside, then empty the vacuum bag.
- Hose clusters off walls with a strong spray of water; they’ll return if the spot stays warm.
- Clear piles of lumber, rocks and trash near the house.
When to call a pro
University of Maryland Extension says an insecticide is not necessary or recommended, and Penn State Extension advises against using one indoors once the bugs are in wall voids or attics. If you want an exterior treatment, Penn State says it should be applied by a licensed pest control operator in the fall, just before the bugs gather.
Boxelder Bugs: common questions
Are boxelder bugs dangerous?
No. They aren’t harmful to people or pets, and they don’t bite or reproduce indoors. Squashed bugs may stain fabric.
Why are they all over my sunny wall in the fall?
In fall they gather on the sunny, south-facing sides of buildings, porches and window frames, looking for cracks where they can spend the winter.
How do I get rid of the ones inside?
Vacuum them up and empty the bag afterward, and seal gaps with caulk and weather stripping. University of Maryland Extension says an insecticide isn’t necessary or recommended.
Where in Delaware
Where boxelder bugs rank on each county’s top-pest list:
- New Castle County Not in the county top six
- Kent County Not in the county top six
- Sussex County Not in the county top six