Boxelder bug
Boisea trivittata
- Identification
- Black with red-orange lines and edges, about ½ inch. Congregate on sunny surfaces near boxelder, maple, and ash trees.
- Lifecycle & behavior
- Feed on tree seeds in summer; adults gather on warm walls in fall and overwinter in structures.
- When it's active in Central NY
- Cluster on the south side of CNY homes in fall, especially near host trees, then work into walls and emerge indoors on warm days.
- Risk & damage
- A nuisance only — no biting, breeding, or damage indoors; can leave stains if crushed.
- Why DIY falls short
- Removing host trees is drastic and often impractical; interior spraying is ineffective against wall populations.
- How we treat it
- Timed exterior barrier and sealing, addressing them alongside the other overwintering pests.
Boxelder bug or something else?
Boxelder bugs are unmistakable once seen: about half an inch, flat and elongated, black with three bright red-orange lines on the thorax and red edging outlining the wings. Nymphs are bright red. Nothing else in the fall invasion looks like this — stink bugs are shield-shaped and mottled brown, lady beetles are round and orange.
Boxelder bugs in Central New York
The name is literal and diagnostic: they feed primarily on boxelder trees, along with other maples and ash. If you have a heavy recurring boxelder bug problem, there is very often a female boxelder or maple within a short distance of the house, and identifying that tree explains the pattern.
They gather in large numbers on warm sunny walls in fall — south and west sides again — and slip into wall voids to overwinter, reappearing on warm days. They do not bite, do not damage the structure, and do not breed indoors, but their fecal spots can stain light surfaces.
Dealing with boxelder bug?
Our overwintering pest control handles it — guaranteed, family-owned, and local.
Boxelder bug — common questions
Why does my house get boxelder bugs and my neighbor's does not?
Usually a host tree. They feed on boxelder and other maples and ash, so a female boxelder or maple near your house concentrates the population there. Sun exposure matters too — they gather on warm south and west walls, so a sunny elevation collects far more than a shaded one.