The brown marmorated stink bug (Halyomorpha halys) is an invasive species that has established itself permanently in southern Michigan. Native to Southeast Asia, the brown marmorated stink bug arrived in the US relatively recently. The stink bug species was first discovered in the US in Allenstown, Pennsylvania in 1998. Since then, the bug has spread to nearly every single US state.
Since appearing in Michigan, the brown marmorated stink bug has become notorious for three reasons. First, they tend to congregate together on warm surfaces in very large groups. Second, they inflict significant damage on important farming crops. Then there’s the stink bug’s namesake: brown marmorated stink bugs secrete a disgusting smell when threatened or crushed. Here’s everything you should know about Michigan’s newest pest, and how to prevent them from stinking up your property.
What is a Stink Bug?
Stink bugs are a family of insects called Pentatomidae belonging to the order Hemiptera, or “true bugs.” Like other true bugs, stink bugs use sucking mouthparts to extract sap from plants. Stink bugs are infamous for their ability to secrete an unpleasant-smelling liquid from porous glands located beneath their thoraxes. These secretions smell because they contain the chemical compounds “trans-2-decenal” and “trans-2-octenal.” The secretions smell like coriander, rotting vegetables, or cilantro, depending on who you ask.
The specific stink bug common in Michigan is the brown marmorated stink bug. Brown marmorated stink bugs (or “BMSBs”) just happened to stow away on packing crates in-bound to the US from China or Japan. The brown marmorated stink bug acclimated to the US very quickly and began reproducing and spreading. Today, BMSBs have permanently established themselves as an invasive pest. They’re here in the US–and Michigan–to stay.
Additional Pest Information
Brown marmorated stink bug
Appearance — Brown marmorated stink bugs are small, shield or leaf-shaped bugs that measure between .5 and .75 inches long. Their bodies are several different shades of brown, giving them a marbled-looking appearance. They also have smooth shoulders, alternate black-and-white striping along their abdomen, and white stripes along their legs and antennae. BMSB antennae have five segments.
Biology — Stink bugs are native to tropical environments, so they’re even more sensitive to temperature changes than native pests. Starting as early as September, large numbers of stink bugs begin congregating on warm, reflective or sunny surfaces. You may encounter large congregations of stink bugs on windows, eastern-facing walls, or any other reflective, sunny surfaces. During fall, stink bugs may inadvertently infiltrate homes while seeking out these warm places. Inside, stink bugs make their way to secluded areas and enter a hibernation-like state called torpor for the winter. In spring, stink bugs will wake up and attempt to leave your home.
Prevention — Most stink bugs enter homes by finding cracks near the window and door frames where they congregate. Seal cracks in frames with caulk and repair or replace damaged weatherstripping and screens. Stink bugs may also fly in through air vents or chimneys that expel warm air. Place wire-mesh screens over these openings to keep stink bugs from accessing them.
Are Stink Bugs Dangerous?
Not to people. Stink bugs are never aggressive and they don’t bite, sting, or otherwise hurt anyone. Their secretions smell bad and may trigger minor allergic reactions in some people, but they’re not seriously harmful, either.
Stink bugs are a more serious problem for farmers than they are for homeowners. The BMSB feeds on vegetable, fruit, nut, and legume crops, inflicting significant damage in the process. The BSMB is considered an economically-significant pest to farmers in the mid-Atlantic region of the US.
Stink Bug Control Tips
1. Seal cracks near window and door frames using caulk and replace damaged weatherproofing.
2. Cover vents and chimneys with wire-mesh screens. Replace any damaged or worn out screens.
3. Use caulk to seal small cracks that leak warm air outside. Pay special attention to areas around utility lines, baseboarding, roofing shingles, and the foundation.
4. Wipe down surfaces stink bugs congregate on with ammonia or soapy water. The soap helps remove pheromone secretions that help attract other stink bugs to a congregation site. The smell may also help repel stink bugs.
5. Use a vacuum to pick up any stink bugs you find in or around your home. Do not crush the stink bugs. Carefully throw away the vacuum bag outside when you’re finished.