Boxelder bugs are black with red markings on their body. They look similar to red fire bugs and other related groups. Immature forms are smaller but easily distinguished from the adults by their lack of wings and red abdomens.
Boxelder bugs are a nuisance, but they are not a health threat. They congregate on exterior walls of buildings in spring and fall and can come indoors and annoy occupants. They overwinter in cracks and crevices in buildings. They also may stain lightly colored materials.