Boxelder bugs are primarily a nuisance because they enter homes and other buildings, often in large numbers. Fortunately, they do not bite people and are essentially harmless to property. When abundant, they can stain walls, curtains, and other surfaces with their excrement. Occasionally some may seek moisture and may be found around houseplants, although they rarely attack them. In the few cases when they do feed, boxelder bugs are very unlikely to injure indoor plants.