Brown Marmorated Stink Bug in New Hampshire — ID & Control

The brown marmorated stink bug wears two hats in New Hampshire, and conflating them is the number-one reader mistake. Outdoors and on farms it is a serious, economically significant agricultural pest capable of damaging hundreds of plant species. Indoors in your home, it is a pure nuisance — it won't bite you, won't breed in your walls, won't damage your house or stored food, and has no credible human-health threat. The cilantro-like odor it releases when disturbed is unpleasant, not dangerous.

The NH-seasonal story: BMSB masses on warm, sunny building walls roughly September 1–20, ahead of Manchester's first hard frost (~Oct 19 at 50% probability per NOAA 1991–2020). It slips inside through any gap it can find — utility penetrations, window trim gaps, soffit seams — and overwinters in wall voids. On warm late-winter or early spring days, overwintered adults emerge near windows seeking the outdoors. First confirmed in NH at Portsmouth in the summer of 2010, it was found in more than 20 NH towns and cities by February 2015 (UNH Extension).

The one-second NH ID: check the antennae. Bold, alternating light-and-dark bands = BMSB. Uniform antennae = a harmless native stink bug. UNH Extension rates the antennal check as the single most reliable field ID. The durable household fix is exclusion — caulking entry points before early September — not insecticide spray, which UNH does not recommend for this nuisance and which BMSB resists.