The brown marmorated stink bug (BMSB), Halyomorpha halys, has become a familiar, unwelcome guest in homes across the United States, especially during cooler months. Originating from Asia, this invasive insect is recognizable by its distinctive shield-shaped body, mottled brown coloration, and alternating light and dark bands on its antennae and abdominal edges. While generally harmless to humans and pets, they are well-known for releasing a pungent, unpleasant odor when disturbed, a defensive mechanism that gives them their name. This characteristic odor is a significant nuisance for homeowners, leading many to wonder if the presence of one stink bug signals the arrival of more.
How Stink Bugs Attract Each Other
Stink bugs attract others of their kind through a chemical communication system. They primarily use chemical signals called pheromones, which are released into the air. For the brown marmorated stink bug, adult males are the primary producers of a specific type of pheromone known as an aggregation pheromone. This pheromone is composed of two main chemical compounds, often referred to collectively as murgantiol, with a specific ratio of these isomers being most attractive.
These aggregation pheromones signal the presence of resources, such as feeding sites or suitable locations for overwintering. This chemical beacon also plays a role in attracting both males and females for mating, making it a combined aggregation and sex pheromone. Other stink bugs detect these airborne chemical signals through their antennae, guiding them towards the source. This collective behavior is crucial for the survival of the species, allowing them to locate partners for reproduction and find protected places to survive colder temperatures in large groups. Researchers have been able to synthesize these pheromones, using them in traps to monitor stink bug populations.
What This Means for Homeowners
The aggregation behavior of stink bugs has implications for homeowners. As temperatures begin to drop in the fall, brown marmorated stink bugs actively seek sheltered locations to spend the winter in a state of inactivity known as diapause. Homes and other structures provide ideal overwintering sites, offering protection from the elements.
When a few pioneering stink bugs locate a suitable entry point or a desirable spot within a home, they release their aggregation pheromones. This chemical signal acts as a powerful invitation, drawing many other stink bugs to the same location. Consequently, what might start as a few individual insects can quickly escalate into a noticeable infestation, with dozens or even hundreds of stink bugs suddenly appearing on or inside walls, around windows, or in attics. This explains why homeowners often experience a sudden surge in stink bug numbers, as the insects communicate and congregate in response to these invisible chemical cues. While they do not reproduce or cause structural damage inside homes, their sheer numbers can be a significant nuisance.