The brown marmorated stink bug (BMSB), Halyomorpha halys , is a non-native, invasive insect recently discovered in North America. It is a pest of fruits, vegetables and farm crops. It becomes a nuisance pest when it invades structures to find a place to overwinter.
BMSB is a native insect of China, South Korea, Japan and Taiwan. The first BMSBs in the United States were found in Allentown, Pennsylvania in the 1990s. It is suspected that they were on fruit shipped in packing crates from Asia. BMSB was detected in West Virginia in 2004. BSMB is now found in at least 46 states from Maine to California. It is expected to expand its range across North America.
Adults are about ¾-inch long and shaped like a “shield.” They have varying shades of brown on both the upper and lower body surfaces. They differ from other stink bugs in that they have two white bands on the antennae. Stink bugs get their name from the scent glands located on the dorsal surface of the abdomen and the underside of the thorax.
BMSBs have small, elliptical-shaped eggs that are light green in color. They attach in rows on the underside of leaves in masses of approximately 28 eggs.
There are five immature stages known as nymphal instars. They range in length from 1/8 inch at the first stage to ½ inch at the fifth stage. They have orangish red and black abdomens in the first stage, progressing to off-white and black in the fifth stage. The legs and antennae are black with white bands.
The insect feeds on a variety of fruits, vegetables and farm crops. When BMSB feeds on produce, it causes blemishes and deformations which make it unappealing and unmarketable as a fresh product. Significant losses have occurred for farmers whose crops have been hit by BMSB.
Although BMSBs do not pose a health threat to humans, once they enter a home they can cause alarm while flying around and emitting a strong odor when they are crushed.
BMSBs become a nuisance for most people when they begin looking for warm places to spend the winter. The insect’s behavior is similar to that of the multicolored Asian lady beetle as it is attracted to the outside of houses on warm fall days, especially following the first frost. BMSBs look for any entry point they can find into a structure. Cracks as small as 1/16 to 1/8 inch around windows, doors, eaves and overhangs, dryer vents, and other areas provide a means of entrance.
The best method of controlling BMSBs is to prevent their entry into your home. Caulking with a silicone or silicone-latex caulk around window and door frames and replacing damaged window and door screens will help. Use weather stripping around windows and doors and remove window air conditioners following summer use. Exterior applications of insecticides may be used in conjunction with exclusion techniques when BMSB are actively searching for entry into homes. However, insecticides used alone are likely to provide only limited control.
Once BMSB enters a home, the best methods of control are to vacuum, or knock insects into a bucket of soapy water where they can drown. The best vacuums to use are handheld or bagless because the container can be emptied each time. If you have this type of vacuum, be sure to drop them into soapy water, which will kill the insects. Releasing the insects outdoors will likely result in them eventually coming back into the home. It is not recommended to use insecticides indoors because the insects can avoid the chemicals by retreating into cracks and crevices. Also, the insecticide itself may be hazardous to humans and pets.
Although BMSB are a nuisance to homeowners, they do not cause any significant structural or cosmetic damage, and will not reproduce inside the home.
BMSB has one to two generations per year in West Virginia depending on temperatures. Adults overwinter in protected sites including homes. In the spring, adults emerge from overwintering sites to feed and mate. Nymphs and adults can typically be found feeding on host plants throughout the growing season.
Author: Daniel Frank, WVU Extension Service Entomology Specialist
Last Reviewed: May 23, 2017