This is the time of year when brown marmorated stink bug (BMSB) start to head back to their overwintering sites - our homes! It is therefore also a good time to learn how to recognize BMSB from the other bugs that might also try to take advantage of your hospitality for the winter.
The first step to determine if it is at least a stink bug. Other types of insects also make their way into homes. Look at the shape of the insect. All stink bugs are shield-shaped and have a triangle on their backs. But true bugs, closely related to stink bugs, are also shield-shaped and have a triangle. Western conifer seed bugs, box elder bugs, and squash bugs are just a few true bugs that homeowners find and confuse for BMSB. The difference between stink bugs and these other true bugs is that the stink bug's "shield" is almost as wide as it is long (Figure 1). Other true bugs are "skinnier" than stink bugs; that is their shields are longer than they are wide.
Figure 1 - Brown marmorated stink bug adult. Photo credit: Jennifer Read, NRCan
BMSB (and other stink bugs)
- Triangle on back
- Shield-shaped
- Almost as wide as it is long
Figure 2 - Western conifer seed bug. Photo credit: David Cappaert, Michigan State University), Bugwood.org
Western conifer seed bug (and other true bugs)
- Triangle on back
- Shield-shaped
- Longer than it is wide
If you have figured out that you are indeed looking at a stink bug, then you have to look closer to determine if it is BMSB (Figure 2).
Figure 3 - Distiguishing features of brown marmorated stink bug.
Brown Marmorated Stink Bug (BMSB)
- two white bands on each antennae
- smooth shoulders (not saw-toothed)
- legs with poorly defined white band
- abdominal margins have pattern of white inward pointing triangles alternating with dark areas
Source: OMAFRA