The warmer weather of the past week may have brought unwanted visitors to the interior of your home. Warm days waken insects such as boxelder bugs from overwintering areas within the home such as wall voids and attics. Once awake, they travel to a home’s interior, following the warmth. They tend to congregate around windows and other sunny areas.

Outdoors, boxelder bugs feed on low vegetation and seeds on the ground during spring and early summer. They lay eggs on trunks, branches, and leaves, of seed-bearing boxelder trees. During years of high populations, the nymphs may be found on the ground, on mulch, and in the garden in large numbers. During later summer and fall, boxelder bugs search for protected areas for the winter. Boxelder bugs like warm areas and are attracted to buildings with a large southern or western exposure.

Boxelder bugs found indoors during late winter and spring entered the previous fall through gaps or cracks around the building. Boxelder bugs do not reproduce indoors or bite people. They can stain walls, curtains and other surfaces with their excrement. It is best to remove boxelder bugs found indoors by hand or with a vacuum cleaner.

Prevent boxelder bugs from entering your home by checking the exterior for spaces and cracks that may allow insect entry. Install tight-fitting door sweeps or thresholds at the base of all exterior entry doors. Seal openings where pipes and wires enter the foundation and siding using a suitable construction sealant. Repair gaps and tears in window or door screens as well as the screens in roof and soffit vents or bathroom and kitchen fans.

Physical exclusion can be supplemented with an insecticide application around the exterior of your home. The best time to spray is late summer and fall when boxelder bugs begin to cluster around the outside of buildings. You can treat your own home by using an insecticide labeled for the exterior of buildings. A few examples of common names of active ingredients available to the public include bifenthrin, cyfluthrin, deltamethrin permethrin, and tralomethrin. The common name of a pesticide can be found by looking at the label under Active Ingredients. Be sure the product selected is labeled for use on the exterior of buildings.

If you would like more detailed information about boxelder bugs please look at this link: http://z.umn.edu/boxelderbugs or contact me at the University of Minnesota Extension office, Clay County at 218-299-5020, 1-800-299-5020 or email me at nels1657@umn.edu. Check out our website at www.extension.umn.edu/county/clay/.