Western boxelder bug
categories: Fact Sheet Nuisance Pests
revision date: 2025-03-15 08:38
Photo by: J. Brunner
Biology
The western boxelder bug is a flat, slender insect about ½ inch long and ¼ inch wide. The adults’ wings are dark grey to black with conspicuous red lines. The body (beneath the wings) is bright red with a black head, antennae and legs.
While these bugs can be pests of fruit trees and several ornamentals during the growing season (maples seem to be their favorite), they are more of a nuisance pest in late summer and fall when they migrate to overwintering sites which include residences.
Some years there may be large numbers of them on the walls of homes and buildings. They do not pose a threat to buildings, the contents thereof, or to humans.
Management Options
Use Integrated Pest Management (IPM) for successful pest management.
Non-chemical Management
Select non-chemical management options as your first choice!
- They can be collected and disposed of by sweeping or vacuuming.
- Openings around doors, windows, and foundations should be closed off or adequately screened to prevent the bugs from entering the dwelling.
Chemical Management
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.
- None recommended
WSU Extension programs and employment are available to all without discrimination.
Evidence of noncompliance may be reported through your local Extension office.
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