Boxelder Bugs Invade Homes

Boxelder bugs, sometimes called maple bugs, are relatively large insects, about 1/2" long, dark gray in color with red markings on their backs (see photo right). They are harmless but what makes these insects remarkable is their tendency to congregate on houses in the fall of the year, often in enormous numbers. It truly seems like an invasion -- especially the first time it happens.

Here's what's going on. Boxelder bugs have one generation a year. Eggs are laid in early summer on maple trees. Eggs hatch and the young nymphs feed on maple tree leaves during the summer. By fall the insects have reached adulthood with fully developed wings and are ready to migrate in search of a protected place to spend the winter (see The Life Cycle of Boxelder Bugs for more information).

Migrating boxelder bugs are attracted to large trees with dense, evergreen foliage like cedars, or trees with deeply fissured bark. A single large tree might attract hundreds, or thousands, of boxelder bugs from the surrounding area. These bugs are strong fliers so may travel miles from the maple tree on which they developed.

If this tree, full of thousands of bugs, is near the sunny, southwest, side of a house bugs will move onto the warm house during sunny days. Imagine, a thousand, or more 1/2" bugs congregating on the outside of your house, around doors, windows and on siding. This actually happens to many people each fall, year after year.

What to do. First realize that these bugs are harmless. They don't bite or sting, won't hurt your house nor will they set up permanent residence. But, see Boxelder Bug Control on Houses for some suggestions for getting rid of them.

Using Plant-based Botanical Insecticides