Household Fall Invaders

Beetles, bugs, and flies are some of the creatures actively seeking protected overwintering sites as days get shorter and cooler. Many produce stains or unpleasant odors if crushed. Scavengers, such as carpet beetles, can be attracted to accumulations of
insects that die in attics and wall voids. Lastly, overreaction to pests may lead to excessive insecticide use indoors that can have serious consequences.

aggregation of boxelder bug adults and nymphs near foundationThe best strategy is to keep as many as possible from getting indoors. These pest-proofing tips will get you off to a good start: Sealing as many potential entryways as practical keeps bugs, mice, and cold air out. Check for gaps around openings where utilities and pipes enter structures and worn exterior door seals that let creatures crawl in from around foundations or crawlspaces.

Some shelter-seekers will congregate on warm sunny south- or west-facing walls of houses and buildings for a while before crawling around in search of a crack or crevice to enter. When practical, this gives a chance to reduce the number of potential invaders. Direct sprays of insecticidal soap or other insecticides for outdoor pests can kill many before they have a chance to enter. In some cases, an insecticide can be applied around the base of the foundation as a “barrier treatment” to reduce entry by accidental invaders.

A few creatures will get past the best defenses. When that happens, swat and remove them with a dustpan or vacuum. Limit the use of insecticides indoors.

Outdoor, exposed aggregations of accidental invaders provide an opportunity for control before they enter a house or building. Direct application of insecticidal soap, or other appropriate insecticide, should give good control. It is better to try to deal with them before they get indoors, if possible.

Boxelder bug adults and nymphs are most abundant where their food plants (including boxelder, maples, and ash) readily available. Winged adults can arrive from some distance, but if wingless nymphs are abundant then host plants must be close.

Boxelder bugs leave their host plants in the fall in search of cracks and crevices that can provide shelter for the winter. One option is to control them there, before they leave.

The brown marmorated stink bug continues to rise in the pest ratings as its populations
increase and expand across Kentucky. This insect is showing up on exterior walls. Restless crawling will often allow it to find an opening to get inside before settling down. This insect has a wide host range so it will increase as a problem over the state.

Cluster flies are any of several species that spend the winter as adults and move to shelter in the fall. The face fly can come to homes in rural areas in huge numbers. The big buzzing bluebottle flies come in, too, but there usually are only a few of them. As with the rest of these fall invaders, they do not breed indoors, but it certainly
seems that way.

The western conifer seed bug, a leaf-footed bug, has become a common fall invader but not as significant as the brown marmorated stink bug (BMSB). As with the BMSB, the insect does not sting or bite but gives off a distinctive odor if handled. These bugs feed on conifer seeds so they are abundant in landscapes that contain white pine, Scotch pine, Austrian pine, mugo pine, or hemlock.

The multicolored Asian lady beetle is most likely to be at nuisance levels around woods because it tends to prey on sap-feeding insects that infest trees. Asian lady beetles generally do not injure humans and are mainly a nuisance. Like most other accidental invaders, they do not reproduce indoors — those appearing in late winter/early spring are the same individuals that entered the previous fall. Lady beetles do not attack wood, food or clothing. Nonetheless, some householders detest finding any insects indoors, and hygienic establishments such as hospitals have zero tolerance for contaminants of any kind.

lady beetleBesides being a nuisance, the lady beetles emit an acrid odor and can stain surfaces with their yellowish secretions when disturbed (volatile compounds used in defense against bird and other vertebrate predators). Although Asian lady beetles do not transmit diseases per se, recent studies suggest that infestations can cause allergies in some individuals, ranging from eye irritation to asthma.

People should avoid touching their eyes after handling the beetles, and should consult a physician if they suspect they are having an allergic reaction. When large numbers of beetles are flying in the fall, they often land on clothing and occasionally will bite or ‘pinch’ if in contact with skin. In nature, lady beetles eat other insects and have chewing mouthparts. The bite feels like a pinprick and is seldom serious.

It is impossible to keep all invaders out but an aggressive pest-proofing program is an important part of managing them.

Submitted by Lee Townsend and Mike Potter, Extension Entomology Specialist’s, University of Kentucky, Department of Entomology