Brown Marmorated Stink Bug
(Halyomorpha halys)
Shield-shaped invasive insects that enter homes in large numbers in fall and release a foul odor when disturbed.
Overview
The brown marmorated stink bug is an invasive species from Asia that has become a major fall nuisance pest in Bowling Green. As temperatures drop in autumn, stink bugs seek sheltered overwintering sites — and homes are a top choice. They can enter structures by the hundreds or thousands, congregating on south- and west-facing walls before squeezing through tiny gaps. They do not bite, sting, or cause structural damage, but they release a pungent, cilantro-like odor from glands on their abdomen when disturbed or crushed.
Appearance
Stink bugs are about 5/8 inch long with a distinctive shield-shaped body. They are mottled brown and gray with lighter bands on the antennae and darker bands on the outer edge of the abdomen. Their body is nearly as wide as it is long. The brown marmorated species is distinguished from native stink bugs by the alternating light and dark bands on the antennae.
Habitat
Stink bugs are agricultural pests during spring and summer, feeding on fruit trees, vegetables, and ornamental plants. In fall, they migrate to structures for overwintering, often congregating in huge numbers on sunny exterior walls. Once inside, they shelter in wall voids, attics, behind baseboards, and in other protected spaces. They become active again on warm winter days and emerge fully in spring to return outdoors.
Diet
Stink bugs are herbivores that feed on over 100 species of plants. They use piercing-sucking mouthparts to feed on fruits, vegetables, and ornamental plants, causing dimpled, discolored damage. Common host plants include apples, peaches, tomatoes, peppers, and soybeans. They do not feed on anything inside homes.
Lifecycle
Adults overwinter and become active in spring. Females lay clusters of 20 to 30 barrel-shaped eggs on the undersides of leaves. Nymphs go through five instars over about 5 weeks before reaching adulthood. One to two generations are produced per year in Kentucky. Adults begin seeking overwintering sites in September and October.
Signs of Infestation
- !Large numbers of shield-shaped bugs congregating on south- and west-facing exterior walls in fall
- !Live or dead stink bugs appearing indoors during fall, winter, and early spring
- !A strong, unpleasant odor when bugs are disturbed, vacuumed, or crushed
- !Stink bugs clustering around windows and lights on warm winter days
Prevention Tips
- ✓Seal cracks around windows, doors, siding, utility pipes, and roof soffits before fall
- ✓Install or repair window screens and door sweeps
- ✓Caulk around window air conditioning units and exterior fixtures
- ✓Reduce outdoor lighting on the south and west sides of the home in fall (lights attract them)
- ✓Apply professional-grade exterior perimeter treatments in early to mid-September before migration begins
Professional Treatment
The most effective treatment is a well-timed exterior perimeter application in early to mid-September, before stink bugs begin entering the structure. Once inside wall voids, treatment options are limited — vacuuming live bugs is the most practical removal method. Sealing all entry points is critical for long-term prevention. Interior pesticide applications are generally not recommended because dead bugs in wall voids can attract carpet beetles.
Did You Know?
- •The brown marmorated stink bug was first detected in the US in Pennsylvania in 1998.
- •Their defensive odor contains chemicals also found in cilantro.
- •A single home in the mid-Atlantic region recorded over 26,000 stink bugs in one season.
- •They communicate with each other using vibrations transmitted through plant stems.
About 5/8 inch
Mottled brown and gray, shield-shaped
6
Shield or pentagonal body shape
Stink bug, Shield bug, BMSB
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Other Occasional Invaders in Our Library
Boxelder Bugs
Black-and-red bugs that swarm on sunny walls in fall before entering homes to overwinter.
Cluster Flies
Large, sluggish flies that enter attics and wall voids in fall to hibernate in large clusters.
Earwigs
Distinctive insects with rear pincers that hide in moist areas and enter homes during wet weather.
Millipedes
Slow-moving, many-legged arthropods that invade homes in large numbers after heavy rains.