Back to Pests

Boxelder bugs

Content Detail

Common name:  Boxelder bugs

Scientific name:  Boisea trivittata

Hosts:  Boxelder bug’s primary host is boxelder (Acer negundo), but it can also be found on silver maple (Acer saccharinum) and trident maple (Acer buergerianum).

While boxelder bug can cause minor damage to its preferred host plant, the boxelder tree (Acer negundo), it is primarily a nuisance for the homeowner. The insect overwinters as adults, who must find warm, protected sites. Boxelder bugs will seek access to warm buildings through any cracks or crevices in foundations, doors, and windows, and it is their presence indoors that poses a nuisance. Boxelder bugs are found throughout the United States.

Boxelder bugs are sap feeders and will suck the sap out of boxelder seeds, and sometimes leaves. They are most often found on the female trees, since they prefer to feed on seeds. The boxelder bug’s feeding will damage and distort the tender young leaf growth, but overall does relatively little damage to the host tree.

They are a bigger problem as a nuisance pest indoors. In addition to being an annoyance, they can also stain fabrics and walls with their excrement. If crushed, they also leave a stain. Boxelder bugs do not bite humans and they do not spread disease. They do not breed indoors.

Boxelder bugs overwinter as adults in homes and other protected sites. In early spring (usually, late April to early May), the adult female emerges from her overwintering site to lay eggs on the young leaves and seed pods and in bark crevices of the boxelder tree. The freshly laid eggs turn from yellow to red as the embryo develops. Once the nymphs appear in late spring to early summer, they develop rapidly, feeding on the seeds and immature leaves of the boxelder. An adult female can produce one to two generations per year before seeking a place to hibernate for the winter. It is during this process of looking for overwintering sites that the boxelder bug is most commonly seen, and on a warm autumn day, you will find them congregating on the sunny sides of tree trunks and buildings.

The adult boxelder bug is oval-shaped, ⅜ to 5/8 inches long, and distinctively marked with red lines, one down the center and one on each side of the thorax, as well as on its front wings. Its base color can be dull black to charcoal gray. At the immature (nymph) stage, it is bright red with small dark wing pads being added as it grows.

Cultural management: 

The most effective way to manage boxelder bug infestations is to remove the primary host plant, the boxelder tree, especially ones growing near foundations and buildings. If that is not an option, then diligence in sealing cracks and crevices around windows, doors, and building foundations is the next best method to eliminate their access to your home. They can be removed indoors by vacuuming. Avoid crushing them as it will result in a permanent red stain.

Chemical management:

Damage to the host tree is very minor and so no chemical treatment is warranted.

For more information, contact The Morton Arboretum Plant Clinic (630-719-2424 or