Box elder bugs are traditionally an insect that cause concern in the fall months. As the weather cools, they tend to congregate on the warmer, sunnier sides of houses and buildings. This spring, however, a large number of immature nymphs congregating in flower beds and rock gardens are raising a few eyebrows and causing gardeners to wonder what these little red bugs are. Here is what you can do now to minimize a box elder bug outbreak later this fall:

Adult box elder bugs are about half an inch long, dark brown to black insects with reddish-orange markings on their back. The immature nymphs are generally similar in shape to the adults but are much smaller, bright red and lack wings. Nymphs go through gradual metamorphosis from immature to adult. The youngest nymphs are solid bright red with jet black legs. With each molt, they gain more black markings and finally develop wings when they reach maturity.

Box elder bugs have to overwinter as adults. To do so, in the late summer and early fall, the bugs move to warm sheltered areas. They become household pests as they crowd into cracks and crevices on the south and west sides of buildings, patios and concrete walls – eventually making their way into wall voids and ending up in homes.

In the spring, adults emerge to search for female box elder trees. They deposit eggs in the cracks of the bark. Newly hatched nymphs find their way to tender young leaves and begin feeding. They also may feed on flowers and, later, on the seeds.

Although the adults will not bite or damage buildings, furnishings, clothing or food, they can spot curtains and walls with fecal material and leave a stain if crushed. Box elder bugs are mainly a nuisance pest; they crawl and fly about rooms and accumulate around light fixtures in the home.

Control is not simple but needs to start now. Begin by insect-proofing your home. Caulk cracks and crevices, around vents, and other gaps on the exterior of the home.

Second, check all screens and storm doors. Make sure they fit snug and secure. Finally, clear the yard of clutter. Lumber, stored firewood and similar materials can serve as a source of overwinter shelter.

Boiling water can be poured on small masses of bugs. Take extreme caution not to scald yourself during the process. Likewise, a mild liquid soap solution can be sprayed on adults and nymphs. Take care not to spray valuable landscape plants as the soap may damage the foliage.

Insecticides, such as Sevin, Cyfluthrin and malathion work marginally at best. Choose an outdoor spray concentrate or a ready-to-use product listing box elder bugs or similar nuisance pests on the label. Choose products that are safe to spray on both ornamental plants and outdoor building surfaces.