Battling boxelder bugs in the springtime

If you are like me, I am ready for spring and for the boxelder bugs, boisea trivittatus, to go away.

This year is the first year in a long time I have had to deal with boxelder bugs in the office. If you have lived any time at all in Wyoming you have had or will deal with boxelder bugs.

Adult boxelder bugs are about 1/2-inch long, black with orange or red markings, including three stripes on the prothorax, the area right behind the head. Their wings lay flat over their bodies, overlapping each other to form an X. The immature nymphs are one-sixteenth-inch long and bright red when they first hatch. As they grow older and become larger, they are red and black.

You can potentially see all stages at any given time during the summer.

Fortunately, boxelder bugs do not bite people.

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 Wyoming, boxelder bugs emerge from hibernating sites during spring as the weather starts to warm up. Adults feed on low vegetation and seeds on the ground during spring and early summer, and begin mating a couple weeks after they have started feeding. Starting in mid-July, they move to female seedbearing boxelder trees where they lay eggs on trunks, branches, and leaves. Boxelder bugs may also feed on maple or ash trees. There is no noticeable feeding injury to these trees. I have seen boxelder bugs all over Wyoming; even far away from any boxelder tree.

During late summer and fall, boxelder bugs start to leave the trees from where they were feeding to find protected areas for the winter. Adult boxelder bugs typically can fly several blocks, although in some cases they can travel as far as two miles.
Some homes are especially attractive to boxelder bugs, while neighboring buildings may have few. This usually depends upon the amount of sunny exposure a building receives. Boxelder bugs like warm areas and are attracted to buildings with a large southern or western exposure. As the weather cools, boxelder bugs push into cracks and spaces around homes. In some cases, they end up in the interior of buildings where they are often found around windows. During winter, boxelder bugs are generally inactive.

They enter a home’s interior from overwintering areas within the home, e.g. in walls or attics. As they wake up, they follow the warmth into the home’s living quarters. However, the warmth does not reach the insects equally and they do not all become active at the same time.

The best management of boxelder bugs is prevention — take steps to keep them from entering your home from the start.

Seal up any cracks or opening especially around windows and doors.
If you spray around the exterior of your home, make sure you spray around all doors and windows on the west or south facing sides.
The best time to spray is late spring and fall when boxelder bugs are first clustering around the outside of buildings.

Examples of chemical/common names of active ingredients available to the public include:
• bifenthrin (Talstar)
• cyfluthrin (Tempo)
• deltamethrin (Suspend)
• lambda cyhalothrin (Warrior)
• permethrin (Ambush)
• tralomethrin (Chemsico)
• Lemon scented liquid soap offers safe, effective control when applied directly to the insects.

Removing the seed-bearing boxelder trees in your yard is not a practical solution for boxelder bug management because adult boxelder bugs can fly up to a couple miles from food.
Trade or brand names used in this publication are used only for the purpose of educational information.

The information given herein is supplied with the understanding that no discrimination is intended, and no endorsement information of products by the University of Wyoming Extension is implied.
Nor does it imply approval of products to the exclusion of others, which may also be suitable. The University of Wyoming is an equal opportunity/affirmative action institution.

Scott Hininger is with the Sheridan County Extention office.