The brown marmorated stink bug (Halyomorpha halys) is an invasive species that has become a significant agricultural and household nuisance across the United States. Originating in East Asia, this pest successfully established itself in temperate climates due to its remarkable ability to survive the winter months. The answer to whether stink bugs can survive the cold is a definitive yes, which is tied to their success as an invading organism. Their survival hinges on specific behavioral strategies and internal biological mechanisms that protect them from lethal temperatures.
The Overwintering Strategy
As the days shorten in late summer and early fall, the brown marmorated stink bug begins preparation for winter. This preparatory phase is known as diapause, a state of dormancy distinct from simple hibernation. Diapause is triggered by a reduction in daylight hours (around 11 to 13 hours of light), signaling the impending cold season.
During this period, the adult insects cease feeding and reproduction, leading to a metabolic slowdown. This metabolic suppression conserves the energy reserves needed to sustain the bug when food is unavailable. The most visible part of this strategy is aggregation behavior, where stink bugs gather in large groups to seek sheltered, dry, and dark locations.
These aggregation sites serve as thermal refuges, shielding the insects from outdoor temperature extremes. Preferred locations include natural shelters, such as under loose bark or in leaf litter, but they utilize human structures. Buildings, sheds, attics, wall voids, and vehicles provide insulated spaces that remain consistently warmer than the outside air, enhancing survival. Seeking these protected environments is the most important factor in their ability to endure harsh winters.
Physiological Adaptations to Low Temperatures
The stink bug’s internal biology complements its behavioral strategy by preparing its body for the cold of its sheltered microhabitat. Diapause is a prerequisite for the insects to achieve maximum cold tolerance. This physiological conditioning allows them to withstand temperatures lethal to non-diapausing individuals.
The insect’s survival strategy is categorized as chill-intolerance, meaning they cannot survive the formation of ice crystals in their body fluids. They resist freezing through supercooling, which lowers the freezing point of their hemolymph. This is accomplished by accumulating cryoprotectant compounds, such as polyols like glycerol or sorbitol, that act as biological antifreeze to reduce the temperature of ice crystallization.
The average supercooling point for the brown marmorated stink bug is low, measured around -12.6 degrees Celsius (9.3 degrees Fahrenheit). This adaptation is only effective if the insect is protected from external moisture and prolonged exposure. The combination of a lowered freezing point and metabolic suppression allows the insect to survive in stable, cold conditions until spring.
Why Cold Weather Does Not Eliminate Infestations
Outdoor winter temperatures fail to eliminate stink bug populations primarily because they exploit human-made structures as overwintering sites. While the insects are physiologically hardy, surviving cold snaps depends on finding a thermally buffered environment. Studies show that outdoor populations, even in protected natural areas, can experience 100% mortality in a harsh winter.
Individuals that aggregate inside homes, garages, or agricultural buildings are insulated from extreme fluctuations. The lethal temperature threshold involves prolonged exposure to temperatures below -10 to -15 degrees Celsius (5 to 14 degrees Fahrenheit). These temperatures are rarely sustained in the wall voids or attics of a heated structure. Consequently, a mild or typical winter is insufficient to reduce the population effectively, setting the stage for large-scale re-infestation the following spring.
This reliance on shelter means that the most effective non-chemical control strategy is prevention and exclusion. Homeowners should focus on sealing all potential entry points into the structure during the fall, before the bugs begin their overwintering search. This involves repairing damaged window screens, sealing cracks around utility pipes and air conditioning units, and ensuring doors have tight seals. Closing these openings prevents the insects from accessing the warm, protected refuge they need to survive the winter and emerge as a pest the following season.