Factors Influencing Behavior of Overwintering Brown Marmorated Stink Bugs (Halyomorpha halys) in Human Dwellings

The brown marmorated stink bug (Halyomorpha halys) (Stål) is known for overwintering in human homes. Studies were conducted to understand the behavior of adult bugs in response to characteristics of potential overwintering structures including gap sizes, light, and presence of dead conspecifics. In a test where bugs were placed in increasingly tight boxes, most bugs settled in gaps 4.5 - 5.5 mm high. None settled in a space less than 3.5 mm high. In boxes with constant tightness, bugs tended to move to the back, and primarily settled along walls and in corners. In both box types, bugs tended to turn and face the cavity entrance during settling. In tests of responses of disturbed overwintering bugs to common household light bulbs over the course of a year, bugs were taken from shelters and exposed to lit bulbs. Bug responses were seasonal, with attraction to light bulbs in spring and summer, but little or no consistent response in fall or winter. The lack of response occurred more often at night than in afternoons. Because not all bugs survive the winter, corpses can accumulate. Single shelter-seeking H. halys were found not to respond to the presence of dead aggregations from the previous years unless touch was possible, in which case aggregations were joined. Dead aggregations from the same year had a repellent effect. Presence of a single dead bug from the same year did not provide any survivorship advantage to overwintering bugs. Results suggest possible improvements to trap shelters.