We either had a bumper crop of boxelder bugs last year or they’ve made an evolutionary leap in intelligence and become much more capable of getting inside my house. There are always a few boxelder bugs roaming the interiors of many Missouri houses and buildings over the winter, but I don’t ever remember seeing several per day every day.
Boxelder is a native Missouri tree in the maple family. During the growing season, boxelder bugs will feed on the leaves, flowers and fruits of boxelders and silver maples. Neither of those species are considered good landscaping trees, even if not for hosting this pesky insect. Boxelder trees are seldom planted; but they spread easily through the winged seeds produced by the female trees, so they are commonly found in home landscapes.
During the summer, boxelder bugs lay eggs in the crevices of tree bark. These hatch into red nymphs that mature into adults by late summer. We usually first notice the bugs after the first cool days of fall, when they congregate by the hundreds or thousands on the sunny sides of trees, homes and buildings. They soon begin to look for overwintering sites to avoid the coming cold. They can fly or crawl to crevices or cracks in houses and eventually, almost magically, find their way into the living quarters where bugs are usually not welcome. Not normally active during the winter, the insides of our heated structures are like spring break in south Florida to boxelder bugs. Unlike spring breakers, they actually do little, if any, damage to people, pets or homes but most folks do tire quickly of seeing them inside.
Potential solutions to box elder bugs include removal of boxelder trees from your property, especially the female, fruiting specimens. Sealing any cracks or crevices on your home that provide access to the inside may help. Once inside, hand-picking them is probably the most efficient means of removal. I’ve never had one bite me and I don’t think they are capable of biting, but someone reading this will contact me and say they’ve been bitten. Vacuuming is also an option but hardly worth the trouble if you only see them one at a time. For a good reference on other control options, see the University of Missouri Extension document.