Before there were stink bugs to disturb our domestic bliss we had the boxelder bug. (Boisea trivittata). The boxelder bug is a native species unlike the brown marmorated stink bug which emigrated from China. Box elder bugs are true bugs that are about ½ long and they have orange and red bands along a black exterior. These bugs can fly up to two miles at a time. Boxelder bugs overwinter as adults, oftentimes in our homes and become active on warm sunny days. Once the adults emerge in the spring they make their way outdoors and look for food. They mate in late spring then females lay eggs on the female box elder tree. Boxelder trees are dioecious they have separate male and female trees.
For the most part the box elder bug congregates on the female tree. Male and female box elders can be differentiated in that only the female can produce the winged seed also known as a samara. Once the eggs hatch a small bright orange nymph arises. As these nymphs enlarge they go through 5 separate moltings “instars” eventually developing into an adult that can fly. Most adult boxelder bugs emerge by late summer. Box elder bugs feed by sucking the sap out of box elder, maple, ash, and ailanthus. This feeding does not harm the host plant. Once fall arrives and temperatures cool down, the adults search out a winter location. It is at this time that these bugs will congregate in very large groups on the side sunny side of outdoor walls, trees, or other structures. Eventually these bugs will try to squeeze through openings in homes and buildings and overwinter inside these havens. It is when they are inside homes or other structures that the box elder bug becomes a nuisance as the congregate in mass or stain walls, curtains, and furniture with their fecal material. Eventually the weather will warm up and the adults will move outdoors where their life cycle begins again.
Box elder bugs are not the widespread nuisance that stink bugs are, but where they are found they can build up to annoying levels pretty quickly. Typically large aggregations of box elder bugs are found where you have a high concentration of female box elders or in homes that receive a lot of sunlight from a south west direction. Managing box elder bugs is much like managing stink bugs in that it is good to seal off crevices leading into the home. Another measure that helps somewhat is removing female box elder trees around the home. When large numbers of box elder bugs congregate in the fall on outside walls or trees they are vulnerable to vacuums, insecticides, and a 3% solution of dishwasher soap and water. Of course having a vacuum ready inside the home is another way to manage both box elder bugs and stinkbugs.
Article by FCFCDB
Nature Notes for 11/6/21