The brown marmorated stink bug (Halyomorpha halys) is an invasive shield-shaped insect from Asia, first found in Pennsylvania in the late 1990s and now common across much of the country. It is both an agricultural pest and a household nuisance that pours indoors every fall. Here is how to know it.
How to Identify It
- A shield-shaped body about 5/8 inch long, mottled ("marmorated") brown
- Alternating light and dark bands on the last two antenna segments — a key mark
- Alternating light and dark bands along the edge of the abdomen
- A smooth "shoulder" edge (no spines), unlike some native stink bugs
Why It Matters
In the garden and on farms, these stink bugs pierce and damage fruit, vegetables, and ornamentals. In fall they gather on sunny walls and slip indoors to overwinter, sometimes by the hundreds — and if you squash or startle them, they release the sharp, cilantro-like odor that gives them their name.
What to Do
- Seal cracks, gaps, and screens before fall to keep them out
- Vacuum up indoor invaders (empty the bag promptly) rather than crushing them
- For gardens, keep an eye on ripening fruit and report severe outbreaks locally
Not sure if that shield-shaped bug on your window is the invasive brown marmorated stink bug or a harmless native? Photograph it and Spotter will tell you which it is in seconds.
Try Spotter Free on iOS & Android
Plants, animals, fungi, and rocks — all from a photo. 5 free identifications every day, no credit card required.