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Boxelder bugs

Quick facts

  • Boxelder bugs like warm areas and are attracted to buildings with a lot of southern or western exposure. 
  • The best time to control them is in the fall and is most effective by sealing openings and the timely use of insecticides
  • They normally do not cause property damage but they can potentially stain surfaces.
  • Once they are indoors, the only practical control is physical removal.
  • They are not a serious problem every year.

Boxelder bugs (Boisea trivittatus) are a nuisance because they enter homes and other buildings, often in large numbers. You might not notice them during summer, but they can become an issue when they try to move into homes during fall to find a warm place to hide for winter. 

Identifying boxelder bugs 

Adult boxelder bug on window screen

Adult boxelder bugs 

  • About 1/2-inch long
  • Black with orange or red markings, including three stripes on the area right behind the head (prothorax)
  • Wings lay flat over their bodies, overlapping each other to form an ‘X’ 

Young boxelder bugs (nymphs)

  • 1/16th-inch long
  • Bright red when they first hatch, they change to red and black as they get larger
Adult and smaller nymph boxelder bugs swarming outside

Boxelder bugs are "true bugs" and belong to the same family as stink bugs, cicadas and other insects with piercing and sucking mouthparts. They release a bad odor when crushed.

You can see bugs at all stages of development at any given time during the summer.  

Boxelder bugs are not a serious problem every year. They are most abundant during hot, dry summers when followed by warm springs.

Life cycle of boxelder bugs

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Keeping boxelder bugs out of your home

The best way to manage boxelder bugs is to keep them from entering your home from the start.

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Jeffrey Hahn, Extension entomologist and Mark Ascerno, College of Food, Agriculture and Natural Resource Sciences

Reviewed in 2018

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