Household pest

Stink bug

Pentatomidae (often Halyomorpha halys indoors)

Shield-shaped true bugs with a triangle on the back. The scutellum is a triangle between the wings — it does not cover the whole abdomen the way a jewel bug’s scutellum does. In North American homes, the usual indoor nuisance is the brown marmorated stink bug, which seeks winter shelter in wall voids and rooms.

Identify a photo

Visible identification features

Shield-shaped body, typically 12–17 mm for brown marmorated adults
Mottled brown (brown marmorated) or green in some outdoor species
Scutellum is a triangle; wings and abdomen remain visible behind it
Alternating dark and light bands on the antennae in brown marmorated adults
White banding on the outer edge of the abdomen (connexivum) in brown marmorated

Why it may be in your home

Most stink bugs live and feed outdoors on plants. Brown marmorated stink bugs enter buildings in autumn to overwinter — in wall voids, attics, and around windows — then appear on warm winter days. They do not nest in kitchens the way German cockroaches do, and they do not feed on blood.

Lookalikes

Jewel bug
Jewel bugs (Scutelleridae) have a large scutellum that covers most of the abdomen, often metallic green, blue, or orange. Stink bugs leave the wings and abdomen visible behind a smaller triangular scutellum.
German cockroach
Cockroaches are longer-bodied, lack a shield-shaped back, and live in kitchens year-round. Stink bugs are wider shields and usually appear as accidental indoor guests in cool weather.

Next steps

If it walked in from outdoors in fall or winter, it is likely sheltering, not infesting food. Vacuum it; do not crush it in the room (they release a lasting odor).
Seal gaps around windows, vents, and siding in late summer if they cluster on sunny walls.
Indoor sprays are a poor fit for overwintering adults already inside walls.
If the insect has a huge shield covering almost the entire back and metallic color, compare with a jewel bug before treating anything.

Sources

Brown Marmorated Stink Bug — Penn State Extension
Brown marmorated stink bug — Northeastern IPM Center / StopBMSB

Updated 2026-08-19. Claims are limited to these sources.