Boxelder Bug—Boisea trivittatus
Boxelder bugs normally feed on leaves, flowers and seed pods of boxelder trees and other trees of the maple family. They cause little damage to their host plant, usually only distorted leaves or damaged seeds. They are considered a pest because they congregate in large numbers, trying to get into homes and structures in the fall, and trying to get out of homes and structures in the spring. They produce no odor and do not damage or injure wood, cloth, fruits, vegetables, humans or pets.
Adult bugs are about 1/2 inch long and 1/6 inch wide. They are black with red lines: one line along each side of the body and diagonal lines on each wing.
Immature bugs are mostly red with black only on the head, legs and front of the body. Both adults and nymphs have piercing, sucking mouthparts.
Large numbers of adults congregate on south and west sides of buildings on sunny days.
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Identification and Control Information
- Utah Pests Fact Sheet: Boxelder Bug (PDF)—Utah State University Cooperative Extension
- Boxelder Bugs (PDF)—University of Minnesota Extension
- Integrated Pest Management Around the Home and Landscape: Boxelder Bug (PDF)—University of California
[Photos, left to right: Joseph Berger, Bugwood.org;Whitney Cranshaw, Colorado State University, Bugwood.org; Whitney Cranshaw, Colorado State University, Bugwood.org]