Box Elder Bugs

Box elder bugs are very familiar to most people, although they are sometimes mistaken for cockroaches. The box elder bug is easily identifiable by their black bodies and orange or red markings on their backs, including three distinctive stripes right behind the head. Adult box elders are about a half-inch long while nymphs will be quite a bit shorter and more red in coloration.

Box elders feed almost exclusively on the seeds of different species of maple, especially the box elder tree, from which they take their name. Usually, they make their home on or very near a box elder or maple tree. They can frequently be seen in very large concentrations (called “aggregations”) while sunning themselves near their home tree.

Box Elder Invasion

Box elders become a nuisance when they invade homes, usually in the fall and the spring. Box elders are initially attracted to houses by the prospect of sunning themselves the warm siding of the house, especially those that get a lot of sun exposure (large southern or western exposures are preferred). Once box elders have identified certain sides of the house as ideal for sunning, they can invade he home through any number of cracks and crevices – a common point of entry is between the threshold and the weather-seal of a doorway. They may overwinter in a house, laying dormant behind walls or siding until warmer weather comes, at which point they will emerge in search of food and water.

Once active in a home, box elders will try to get to windows and other sunny areas. They will eventually try to find their way outside again, but most will end up wandering around inside the home, unable to find a way out. Though box elders pose no risk to humans or plant life in the home, their presence can be unnerving, especially since so many of them can descend upon a home at one time, giving the feeling of truly being “invaded” by box elders.

There are two ways to treat box elders: perimeter and/or surface area treatments to keep the box elders from congregating on or around your home, and interior spot treatments to deal with box elders already present inside the house. The important thing to remember is that, despite the potential presence of a large number of box elders in the home, they do not breed or nest inside the house and pose no danger to human health or property.

What about removing trees?

Spraying or removing the seed-bearing box-elder trees in your yard is not a practical solution for box-elder bug management because adult box-elder bugs can fly up to a couple miles for food. Also, box elder trees (as well as maple and ash) are usually common providing many potential sources of box-elder bugs. In our opinion, the benefits of having these trees in a landscape outweigh the problem of occasional infestations. Remember that although you may encounter large numbers of box elder bugs in a given year, they are not automatically abundant every season.