Brown Marmorated Stink Bugs (BMSB) have dispersed throughout the US and feed on a number of agricultural and ornamental plants. They also like to overwinter indoors.
- Adult BMSBs are shield-shaped, 1/2–5/8 inch long (12-15mm), marbled browns in color, with light banding on antennae, abdomen, and legs. Nymphs are 1/8–1/2 inch (3-12mm) long with red eyes, orange and black bodies in early instars; later instars are predominantly black.
Finding a few indoors suggests a need to check for entryways and to improve exclusion. A large number might be gathering in crawl spaces, wall voids, and above false ceilings, especially near the building’s sunny side. While indoor BMSB are mostly an annoyance, handling crushed stink bugs can cause contact dermatitis. Outdoors, stink bugs damage a wide range of plants, including ornamental and fruit plants.
BMSB were detected in the US in 1998 and are now a widespread, successful outdoor pest of many crops and ornamental plants. In the fall, they gather for protective winter habitat and, without proper exclusion, find their way into wall voids around windows, doors, outlets, light fixtures, and air conditioners.
Overwintered adults generally become active in April when they leave structures to mate. They lay clusters of 20–30 eggs on the undersides of leaves from May through August. Eggs hatch in 4–5 days after deposit. Nymphs go through 5 instars.
Prevention by exclusion is key. BMSB are attracted to vertical structures in their search for protected areas such as under loose bark, or gaps in siding. Vacuuming live or dead bugs is a solution to removal but has a risk of contaminating the vacuum hose with a strong odor! When very large numbers are gathered in the surrounding landscape, treatment options may include professional pesticide applications around the perimeter, particularly eaves, soffits, roof vents, flashing, chimneys, and around doors and windows. However, this is an extreme measure and must be made with much detail to safety and concern for air quality and exposure risk. The problem won’t go away unless gaps are sealed.
In some cases, the use of a trap light employing a glue board will reduce numbers indoors. NOTE: heat from the light unit may increase the odor when these insects release scent under stress. The best treatment is prevention. Prepare for possible problems before the fall.