Stink bugs are a common sight as cooler weather arrives. These insects, particularly the brown marmorated stink bug (Halyomorpha halys), are frequently observed seeking refuge in homes and other structures when autumn temperatures begin to fall. This signals a natural behavioral change in response to environmental shifts.
Stink Bug Survival in Cold Temperatures
Stink bugs are cold-blooded insects, meaning their internal body temperature is regulated by the external environment. As temperatures decrease, their metabolic processes slow down. They do not actively seek cold, but rather endure or avoid it to survive. To cope with cold, stink bugs enter a state of dormancy known as diapause.
Diapause is a physiological adaptation for winter survival, induced by shortening day lengths in the fall. During this period, their reproductive activity ceases, and they conserve energy, becoming inactive and not feeding. While in diapause, the brown marmorated stink bug can tolerate temperatures down to approximately -12.6°C, its supercooling point, the theoretical minimum temperature it can survive before its body fluids freeze.
Overwintering Behavior and Seeking Shelter
As autumn progresses and temperatures drop, stink bugs search for sheltered locations to overwinter. Outdoors, they seek refuge under tree bark, in leaf litter, or within rock crevices. However, human-built structures become attractive overwintering sites due to the warmth and protection they offer from the elements.
Stink bugs enter homes and buildings through various openings. Common entry points include cracks and gaps around windows and door frames, foundations, soffits, and attics. They are drawn to the warmth and light from structures before finding a way inside. Once an individual finds a suitable spot, it releases aggregation pheromones, chemical signals that attract other stink bugs to the same location, leading to large congregations.
Cold Weather’s Effect on Stink Bug Populations
Winter conditions influence stink bug populations, especially for those without adequate shelter. While many individuals seek refuge indoors, prolonged periods of extreme cold outdoors can lead to mortality. Studies indicate that exposure to temperatures around -10°C to -15°C can cause survival rates to drop, with high mortality for unsheltered populations during cold snaps.
Despite this vulnerability, stink bug populations show resilience. Those individuals that successfully locate insulated overwintering sites are more likely to survive, even during harsh winters. The quality of these sheltered spots plays a role in their survival rates, allowing enough to persist and contribute to the population in spring.
Preventing Stink Bug Entry in Fall
Preventing stink bugs from entering homes is achieved through exclusion methods, ideally before cooler weather prompts their search for shelter. Sealing cracks and crevices around the exterior of the home is a step. This includes caulking gaps around windows, doors, pipes, and utility lines.
Repairing or replacing damaged window and door screens can block entry points. Inspecting and sealing foundation cracks, securing crawlspace entries, and ensuring chimneys are capped or screened are preventative measures. Reducing outdoor lighting near entryways can make a home less attractive to these insects.