While brown marmorated stink bug (BMSB) has been seen on buildings since early September, the numbers increased substantially this past weekend. Over the next several weeks, BMSB will gather on buildings in search of suitable overwintering sites. Once inside buildings they will remain active until mid-spring. I collected 532 of these insects from the side of my own home and garage this past weekend.
There are several household insect invaders that enter buildings in fall, including boxelder bugs, multicolor Asian lady beetle, and western conifer seed bug. Each of these causes its own particular indoor issue, from just being a nuisance to the staining that results when the insects are accidentally crushed. The nearly ¾-inch BMSB releases a cilantro-like odor when disturbed. and it may feed on houseplants during the winter months.
In the case of BMSB, as with other household invaders, the best strategy is to prevent the insects from entering a home. Buildings that have had previous problems may be more likely to have future issues, as well. Sealing and screening (1/6 -inch mesh screen or finer) entry points to the attic and basement/crawl space, as well as around doors and windows, will limit the numbers that can enter. Insecticide barrier sprays around the outside of the home may also reduce BMSB numbers. Dr. Mike Potter, UK Extension Entomologist, lists a number of steps that can be taken to protect your home from insect invaders in How to Pest-proof Your Home (Entfact 641).
While indoors during the winter, BMSB try to congregate in various places inside structures. This can be in chimneys, closets, window air conditioning units, attics, behind books on a shelf, etc. The best way to remove them once they gain entry is with a vacuum. A knee-high stocking can be used in the suction tube of the vacuum to reduce the number of bags needed. The stink bugs can be disposed of in a container of soapy water. Various types of light baited/funnel traps and soapy water traps can be used to remove them from dark areas in a home.
Ric Bessin, Extension Entomologist