Forestry officials in Maine and entomologists with the University of Maine’s extension office have been receiving a plethora of calls from residents seeking advice on how to prevent boxelder bugs from invading homes in massive numbers during the late summer and early fall seasons. Boxelder bugs are similar to brown marmorated stink bugs and Asian lady beetles in terms of pest behavior. For example, in response to falling summer temperatures during September and October, boxelder bugs swarm into homes where they seek shelter in various locations, such as beneath furniture, in closets, in attic spaces, and in areas that are difficult to access, like wall voids and beneath floorboards. However, unlike brown marmorated stink bugs and Asian lady beetles, boxelder bugs do not secrete odorous defensive fluids, and they very rarely bite humans.

Boxelder bugs frantically swarm into homes in order to secure a warm habitat where they can overwinter. Some insects naturally overwinter outdoors by entering into a dormant state during the winter before regaining vitality come spring. Many other insects that may or may not survive overwintering outdoors will attempt to overwinter within heated human dwellings. Most boxelder bug specimens that secure indoor shelter before the arrival of winter will dry out and die before the spring season arrives, but some overwintering boxelder bugs survive indoor habitats for surprisingly long periods of time without being noticed by the occupants of infested homes.

Researchers have long wondered how overwintering insect pests manage to survive winters in within human dwellings where food sources are lacking. A recent study revealed that overwintering boxelder bugs survive long periods indoors by cannibalizing their own kind. If overwintering boxelder bugs have enough access to water and enough corpses to feed on they can survive well over two months indoors. Overwintering boxelder bugs sometimes swarm out of their indoor hiding spots on unusually warm winter days, as the insects mistake warm winter days as a sign that spring has arrived. When these indoor swarms occur, boxelder bugs try to escape homes in order to reenter their natural habitat, causing yet another nuisance for the occupants of infested homes. Keeping homes tightly sealed will help to prevent boxelder bugs from entering homes, and since boxelder bugs are attracted to artificial lights, keeping unnecessary house lights switched off during the late summer and early fall seasons will prevent the bugs from gravitating onto properties.

Have you ever witnessed an indoor boxelder bug swarm during the fall or winter season?