The Brown Marmorated Stink Bug (Halyomorpha halys), an invasive species from Asia, has become the insect most commonly associated with home invasions across North America. Adults are characterized by their distinct shield-shape and mottled brown coloration, typically measuring about 17 millimeters in length, roughly the size of a dime. The species gets its common name from a defensive mechanism: scent glands located on the underside of the thorax release a pungent, unpleasant odor when the insect is disturbed, handled, or crushed. This chemical defense serves to deter predators in nature, but inside a home, it becomes a major nuisance for residents.
Understanding Stink Bug Flight Capabilities
Adult stink bugs are fully capable of flight, possessing two pairs of wings that allow them to travel considerable distances. This explains why they appear suddenly and often in large numbers on the exterior of homes in the autumn. Studies using flight mills have demonstrated that while the average flight distance is around 2.0 to 2.4 kilometers over a 22-hour period, some individuals have been recorded covering up to 117 kilometers. Flight is heavily influenced by ambient temperature, with takeoff occurring most often between 15 and 30 degrees Celsius. Despite their strong flight muscles, they frequently choose to walk, utilizing flight primarily for long-distance travel between feeding sites and overwintering locations. When inside a home, they are often described as clumsy flyers that may drop when disturbed.
Seasonal Drive for Seeking Indoor Shelter
The motivation for stink bugs to enter structures is entirely seasonal, driven by diapause, a biological imperative similar to hibernation. As late summer transitions into fall, shortening daylight hours and temperatures below 60 degrees Fahrenheit trigger this migration. They seek a sheltered, stable environment to survive the winter months, as they do not require food or water during this period.
Stink bugs are drawn to warm, sun-exposed surfaces, congregating on the sunny, exterior walls of homes during September and October. Early arrivals release an aggregation pheromone, a chemical signal that attracts other stink bugs to the same location. Once inside, they enter a state of dormancy where their metabolism slows, often hiding in attics, wall voids, or behind baseboards.
They are attracted to light and warmth, which guides them toward windows and doors and eventually into any available crack or gap. This attraction causes them to emerge from hiding on warm winter days, mistakenly sensing that spring has arrived, and move toward light sources inside the living space.
Preventing Entry and Safe Indoor Removal
The most effective strategy for managing stink bugs is proactive mechanical exclusion, meaning physically blocking all potential entry points before the fall migration begins. Inspect the entire exterior of the home, paying close attention to areas where different materials meet.
- Use a high-quality silicone or silicone-latex caulk to seal any cracks, gaps, or crevices wider than a few millimeters, especially around window and door frames, utility penetrations, and siding.
- Ensure all screens on windows and doors are intact and fit tightly within their frames, immediately repairing any tears or holes.
- Install tight-fitting door sweeps on all exterior doors, including garage doors, to eliminate the space underneath the threshold.
- Vents for attics, crawl spaces, and exhaust fans should be covered with a fine-mesh screen to prevent insect entry.
For bugs that have already made their way inside, crushing them must be avoided to prevent the release of the defensive odor, which can linger and potentially attract more bugs. A simple and effective removal method is to use a vacuum cleaner, ideally one with a disposable bag. To prevent the vacuum canister from smelling, secure a knee-high nylon stocking over the end of the hose extension with a rubber band before vacuuming. The captured bugs should then be sealed inside the stocking and immediately drowned in a container of soapy water to ensure they are killed without releasing their odor inside the home.