Pest Information: Brown Marmorated Stink Bugs

The brown marmorated stink bug (BMSB), Halyomorpha halys is an invasive plant feeding pest from Japan, Korea, and China. It was first reported in 2001 from Allentown, Pennsylvania. It has since spread into the mid-Atlantic region, parts of the mid west, and into parts of the north east. It has also established into California and Oregon due to commerce. The brown marmorated stink bug is primarily a pest of crops. However, it has become a nuisance pest whereby elevating its urban pest status. Many county extension offices are requesting that people report the bugs if seen.

This species is a plant feeding bug that feeds on fruits, some ornamental plants, and agricultural crops. It is also an occasional invader of buildings, where it is a nuisance pest. They do not bite or sting humans or animals. Adults are approximately an inch long and colored various shades of grey and brown. Their underside can be off-white as well. They can be distinguished from other stink bugs by the alternating color bands on the last two antennal segments and coppery or bluish-metallic colored punctures (small rounded depressions) on the head and pronotum. This species exhibits incomplete metamorphosis. There are five nymphal instars. They range in size from the first instar at 2.4 mm to the fifth instar that is 12 mm in length. The eyes are a deep red. The abdomen is a yellowish red in the first instar and progresses to off-white with reddish spots in the fifth instar.

The BMSB is likely to invade homes in the fall more so than others in the same insect family. It survives the winter as an adult by entering houses and structures when fall evenings start to turn cold. Adults look for buildings to overwinter in order to shield them from the elements. They will work their way under siding, into soffits, around window and door frames, under roof shingles and into any crawl space or attic vent which has openings big enough to fit through. Once inside the house they will go into a state of hibernation (diapause) where they wait for winter to pass. However, often the warmth inside the house causes them to become active, especially in winter months, and they will fly clumsily around light fixtures. Those in diapause will come out of that state in springtime (usually late May, but as early as March in warmer climates) and again become a nuisance pest indoors as they look to go outside and find mates.