Fall invaders stopped at the siding, before they get in the walls.
Brown marmorated stink bugs have spread steadily across southern Wisconsin, and they behave like boxelder bugs and Asian lady beetles: they mass on warm, sunny walls in September and October, then work their way through gaps into wall voids and attics to overwinter. They reappear indoors on warm winter days, crawling across windows and ceilings — which is when most Madison homeowners call us.
Adults are shield-shaped, about three-quarters of an inch, mottled brown, with alternating light and dark bands on the antennae and along the abdomen edge. Native Wisconsin stink bugs look similar but lack the banded antennae. All of them share the defining trait: crushed or threatened, they release a strong, lingering cilantro-and-skunk odor.
Stink bugs do not bite, sting or breed indoors, and they cause no structural damage. The problems are the smell, the sheer numbers a single home can accumulate, and their appetite outdoors — they are a serious agricultural pest of apples, sweet corn, tomatoes, peppers and soybeans, and a heavy population will work over a backyard garden.
Timing decides this one. The effective treatment is an exterior residual applied to south- and west-facing walls, eaves, soffits, window and door frames and other sunning surfaces in late summer, before the bugs move in — once they are inside a wall void, no spray reaches them reliably. We pair that with exclusion work on the gaps they actually use, and for bugs already indoors we vacuum rather than spray, since crushing them releases the odor and can stain.
Late August through mid-September, before the first cool nights drive them to the walls. An exterior treatment applied then prevents the fall invasion; treating in October, once they are already inside the structure, is far less effective.
They are overwintering in your wall voids and attic. A warm spell wakes them, and they move toward light and the living space. That is why exclusion and pre-season exterior treatment matter more than anything you can spray indoors.
No. Crushing releases the defensive odor and can stain fabric and painted surfaces. Vacuum them up and dispose of the bag outside.
Stink Bug control is available across our entire service area at the same pricing and the same response times. That covers Madison and all of Dane County, the I‑94 corridor between Madison and Milwaukee, the full Milwaukee metro — West Allis, Wauwatosa, Franklin, Oak Creek, New Berlin, Muskego and Menomonee Falls — plus Waukesha, Racine, Kenosha, Caledonia, Union Grove and the Janesville–Beloit corridor. No city on this list is an outlying area and none carries a travel fee. Call (773) 263-0887 for stink bug extermination in your city.
Fast, honest, guaranteed pest control across Madison and Dane County.
