Accurate identification of insects around your home is important. This article clarifies how to identify a stink bug by its distinct physical characteristics, helping distinguish them from other common household invaders.
The Signature Stink Bug Appearance
Stink bugs (family Pentatomidae) share several general physical traits. They have a distinctive broad, flattened, shield-like body, earning them the name “shield bugs.” Adults typically measure 0.5 to 0.75 inches long, with some reaching an inch. Their coloration varies, including shades of brown, green, or gray.
These insects have six legs and a pair of antennae, usually about half the length of their body. A prominent feature is the wide, flat back, and their wings typically fold flat over their back, often forming an “X” pattern. The head is generally small in proportion to their body. Stink bugs also have piercing-sucking mouthparts, used to extract liquids from plants.
Identifying the Most Common Invader
Among the various stink bug species, the Brown Marmorated Stink Bug (BMSB), Halyomorpha halys, is the one most frequently encountered by people indoors. Adult BMSBs are characterized by their mottled gray, brown, and black bodies, providing effective camouflage. They typically measure between 0.5 to 0.75 inches (12-17 mm) long.
Key identifying features of the BMSB include alternating light and dark bands on their antennae. Alternating dark and light bands also appear along the thin outer edge of their abdomen, visible even when wings are folded. Their legs are brown. The “marmorated” in their name refers to the variegated or veined pattern on their bodies, resembling marble.
Spotting the Difference: Stink Bug vs. Lookalikes
Many insects are mistaken for stink bugs due to similar appearances or behaviors. Box elder bugs, for example, are confused with stink bugs, but are more elongated and oval-shaped, not shield-shaped. They are black with distinctive red markings along their sides and wings, and are generally smaller, around 0.5 inches long.
Squash bugs also share similarities with stink bugs, both emitting a foul odor when disturbed. However, squash bugs are narrower and more elongated than the wider stink bugs. Adult squash bugs are usually mottled brown or grayish-brown and about 1 inch long. Their abdomen often has orange to orange-brown stripes along the edges.
Certain beetles, like the Western Conifer Seed Bug, might also be confused with stink bugs. Beetles generally have hard outer wing covers that meet in a straight line down their back, unlike stink bugs. The Western Conifer Seed Bug, while also emitting an odor, can be identified by a wide section on each of its hind legs, a feature not present on stink bugs.