Creature Feature

Boxelder bugs are pests of the boxelder tree, a species of maple native to the Midwest. As the boxelder tree was introduced to other areas of the United States and Canada, boxelder bugs followed. The western boxelder bug is present from New Mexico, Utah and Idaho westward to the Pacific coast and up into British Columbia. The boxelder bug is present east of this region in Canada and the United States with some overlap between the two regions. These two boxelder bugs look similar except the western boxelder bug has more red veins on the upper membranous half of its forewings.

Since boxelder bugs prefer to feed on seeds, they are mainly found on female boxelder trees. They will also feed on other maple and ash trees. However, they are not considered major pests because they don’t tend to cause significant damage to valuable ornamentals or agricultural crops. Boxelder bugs are mainly a structural pest in the fall when adults aggregate outdoors on the sunny sides of buildings in search of overwintering sites. On warm winter days and at the start of spring, adults may be found inside buildings as they try to make their way outdoors again.

Pesticide applications are most effective in the fall and should be directed to openings boxelder bugs can use to enter buildings. These openings should be filled or screened for a more permanent solution. Pyrethroid product labels may allow surface treatments for aggregating pests on areas exposed to rainfall above permeable surfaces. In the spring, treat the voids from where boxelder bugs exit into the structure. Also treat the areas where they accumulate as they try to leave the structure, such as around windows and lights.