Of the approximately 250 species of stink bugs in North America, the most common, the most destructive, and the one most likely to show up indoors is the brown marmorated (marbled) stink bug (BMSB). In the late ‘90s, the BMSB was accidentally introduced from Asia into Pennsylvania, most likely in shipping containers. In Asia the bug has natural predators with which it co-evolved. However, in this country, with no natural predators, the BMSB has become a seriously invasive flying pest that has caused severe crop and garden losses and also has become a nuisance in homes. It’s voracious and feeds not only on a lengthy list of host plants, including fruits, vegetables, ornamentals, and soybeans, but also on cotton, weeds and tree leaves.
This stink bug is attracted to homes in autumn when searching for protected, over-wintering sites, especially in attics and other high places. It can enter homes quickly and in the thousands through cracks and open doors or windows and can hitch a ride on clothes and pets. These bugs will not reproduce inside homes (except on the underside of ornamental plant leaves) or cause any damage, but if disturbed or crushed or even sucked into a vacuum cleaner, their smell can be quite pungent and disagreeable (think rotting flesh). In the spring months, the bugs reemerge and actively search for ways to get outside. In the summer months they’ll often gather in large masses on the sides of buildings that receive direct sunlight.
Since its introduction, the BMSB has spread rapidly because of its ability to hitchhike in vehicles and planes and is now found in most states, including Illinois since the mid-2000s. The BMSB is about three-quarters of an inch long and mottled gray-brown in color, has six long legs, striped antennae, and a triangular or shield shape, and is a proficient flier.
Stink bugs are not known to bite or sting humans, but they can produce allergic reactions like rhinitis and conjunctivitis in individuals who are sensitive to the bugs’ defensive chemicals. Insects that are crushed against exposed skin can cause dermatitis at the point of contact.
The best way to keep stink bugs from entering a home:
- use silicone or silicone-latex caulk to seal cracks around windows, doors, siding, utility pipes, chimneys, ceiling fans, electrical outlets, light switches, and underneath wood fascia and other openings
- replace outdoor lighting with yellow bulbs that are less likely to attract to bugs
- repair damaged window screens
- screen attic and crawlspace vents
The BMSB tends to be impervious to pesticides. Their relatively long legs keep them off the surface of plants so the pesticide doesn’t get rubbed off onto their bodies. And, since they eat by sticking a needle-like projection into the interior of plants, the pesticide on the plants’ surface does not get eaten. Home improvement centers sell stink bug traps that work better and are safer than using pesticides. Vacuuming up dead or live stink bugs can result in the vacuum cleaner acquiring the smell of stink bugs.
For infestations in the garden, spraying with a simple mixture of mild soap and water in a spray bottle is effective, especially early in the growing season when the bugs are hungry from not having eaten all winter.