Biology and Identification

BMSB identification flyer (print 2 sided) -espanol.pdf505.87 KB
BMSB identification flyer (print 2 sided).pdf469.51 KB

Brown marmorated stink bug (BMSB) adults are flat insects (approx. 5/8 by 3/8 inches) with drab coloration, although nymphs are brightly colored. Key characters for identifying adult BMSB (photo below) and distinguishing them from similar species, are (1) the distinct light light bands on the dark antennae, (2) smooth "shoulders", and (3) abdominal margins have a distinct banding pattern. If these three characters are present on your Oregon specimen it is BMSB. The common name, marmorated, refers to the color pattern of the insect, which vaguely resembles marble. Like other stink bugs, a foul odor may be produced by BMSB when they are disturbed.

Adult BMSB overwinter as adults (winged) in protected sites in litter, under bark, or in crevices or attics in buildings. They emerge in spring, but may become active on warm winter or early spring days. Mating begins after emergence and the first eggs, laid in clusters of 28, first appear in early summer. There are 5 nymphal instars, or immature development stages, before the the adults stage. All stages except the first instar can cause injury by using the mouthparts, which resemble a hypodermic needle, to pierce and suck the host plant. There is likely to be only one generation in Oregon, but in some regions of the native range of BMSB in Asia, multiple generations per year can occur (photos: Christopher Hedstrom).

BMSB is often mistaken for the very similar looking Rough Stink Bug, Brochymena spp. Some of the differences are noted in the images below: