boxelder bug (20765 bytes)

Boxelder Bug

By Judy Sedbrook, Colorado Master GardenerSM, Colorado State University Cooperative Extension, Denver County

The adult boxelder bug, Leptocorouos trivittatis, is 1/2" in length. Its black and red cross pattern on the back makes this insect easy to distinguish. The boxelder bug sucks the sap from leaves and flowers of its host plants but doesn't cause much damage.

lifestages of the boxelder bug (18794 bytes)

Lifestages of the Boxelder Bug

Most years the number of boxelder bugs found in and around the yard is insignificant. If winters have been mild, large populations may build up and may become a nuisance. The bugs can be found in large groups on the sunny side of tree trunks,  fences, garages and houses. They are most numerous in areas where boxelder trees grow.

boxelder bugs on tree (10120 bytes)

They normally survive the winter by crawling into cracks and holes in bark but also swarm into houses or crawl under siding or cracks in concrete, window and doorsills. They produce no odor nor do they bite. They are harmless and cause no damage other than occasional spotting of windows and draperies.


  • Hot water (165-180 degrees F) applied directly to the insects will kill them.
  • Removing female boxelder trees is the most permanent solution to the problem, although this may not be practical or desirable.
  • A treatment of carbaryl around the perimeter of the tree or house will also provide good control. Remember, always read and follow all label directions before using pesticides.
  • Eliminate hiding places such as piles of rocks, boards and debris near buildings. In the home, hand-collecting, repeated vacuuming or a household spray containing pyrethreins is recommended.
  • Laundry detergents offer a safe, effective control when applied directly to the insects but these may damage vegetation.
  • For long term control, you must deny the bugs access to your home. Carefully inspect your home to determine points of entry and repair these areas.

For more information on boxelder bugs, see CSU Fact Sheet 5.522.

Photographs courtesy of Judy Sedbrook and Kansas State University

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Date last revised: 01/05/2010