Pest guide
Boxelder Bugs
Boxelder bugs are mostly a nuisance pest. They feed on the seeds of female boxelder and maple trees and bask on warm walls in fall before slipping indoors to overwinter. They don't bite or damage structures, but clusters of hundreds can be alarming.
01 — Identification
What boxelder bugs look like
Size
1/2" long.
Color
Black with red or orange edges on the wings and thorax.
Shape
Flattened oval; nymphs are bright red.
How to tell them apart
- Orange 'V' or stripe pattern on the back.
- Nymphs (red, no wings) are often mistaken for a different species.
02 — Life cycle
How they grow and reproduce
One to two generations a year. Adults overwinter and lay eggs in spring.
- 1
Egg
10–14 days
Reddish, laid in cracks of host tree bark.
- 2
Nymph
5 instars, ~7 weeks
Bright red, gradually develop wing pads.
- 3
Adult
~1 year
Overwinters in walls, attics, and leaf litter.
03 — Risks & behavior
What to watch for
Health risks
- Do not bite, sting, or transmit disease.
Home & property risks
- Defensive secretions stain curtains, upholstery, and light-colored siding.
- Mass clusters around windows and in wall voids.
Behavior at a glance
Diet
Female boxelder seeds, occasionally maple and ash seeds.
When active
Day-active; congregates on sunny south- and west-facing walls in fall.
Peak season
Most visible late August through October and again in early spring.
- Removing nearby female boxelder trees drastically reduces populations.
- Sealed structures see far fewer indoor sightings.
04 — Treatment
How to get rid of boxelder bugs
Treat the exterior in late summer before they migrate inside.
- 1
Power-wash siding to remove existing pheromone trails.
- 2
Apply a perimeter spray to sunny walls in late August.
- 3
Caulk siding seams, window trim, and soffit gaps.
- 4
Vacuum indoor clusters — don't crush.
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05 — Prevention
Keep them from coming back
- Treat perimeter in late August.
- Repair torn screens and add door sweeps.
- Trim back boxelder seed pods or remove female trees near the house.
- Seal gaps around utility penetrations.
06 — FAQs
Frequently asked questions
Are boxelder bugs harmful?+
Not directly — they don't bite, sting, or damage structures. The main issue is staining and the sheer numbers in fall.
Why are they on my house?+
South- and west-facing walls warm up first in fall. They congregate on warm surfaces before squeezing inside to overwinter.
Should I remove the boxelder tree?+
If it's a female (seed-bearing) tree close to the house, removal can dramatically reduce populations within a season.
