About Boxelder Beetles (Boisea trivittata)

Activity: Seasonal Home Invaders

Boxelder beetles are outdoor insects that become indoor pests during fall and early spring. As temperatures drop, they gather in large numbers on sunny exterior walls, seeking entry points to overwinter inside homes and buildings. Though they do not bite, sting, or cause structural damage, their sheer numbers and unsightly presence make them a significant nuisance for homeowners.

Diet: What Boxelder Beetles Eat & Why It Matters

Boxelder beetles feed primarily on seeds, leaves, and twigs of certain trees:

• Boxelder trees (Acer negundo)

• Maple trees (especially soft maples)

• Ash trees and fruit trees (occasionally)

While they may cause minor cosmetic damage to foliage, their outdoor activity is generally not harmful. The real concern arises when they invade homes in large numbers.

Size: Distinctive Appearance

• Adults measure 11 to 14 mm in length

• Recognizable by their black bodies with red or orange markings along the thorax and wing edges

• Their flat, elongated shape helps them squeeze into cracks and gaps to enter buildings

While harmless, their habit of gathering in swarms makes them a visual nuisance, especially on the sunny sides of buildings.

Nesting Habits: Where Boxelder Beetles Congregate

Boxelder beetles don’t nest or reproduce indoors but overwinter in:

• Wall voids, attics, and basements

• Cracks around windows, doors, siding, soffits, and rooflines

In spring, they become active again, attempting to exit the building, which can lead to further indoor sightings.

Why Professional Treatment Is Crucial

Though not dangerous, boxelder beetle infestations can:

• Leave behind fecal stains on walls, curtains, and furniture

• Emit an unpleasant odor when crushed

• Reappear year after year if entry points are not sealed

DIY methods like vacuuming only offer temporary relief. Professional pest control provides long-term exclusion and management, preventing recurring invasions.

Signs of a Boxelder Beetle Infestation

Key indicators include:

• Large clusters of beetles on sunlit exterior walls in fall

• Beetles appearing inside windows, ceilings, or light fixtures

• Staining on walls or fabrics from secretions

• Activity peaking during warm, sunny winter days indoors

Understanding the Problem: Boxelder Beetle Infestations

Boxelder beetles exploit:

• Gaps, cracks, vents, and poorly sealed windows/doors to enter buildings

• Once inside, they overwinter in hidden spaces, becoming active again when temperatures rise

Without addressing these entry points, infestations can return each fall, as beetles are attracted by aggregation pheromones left by previous groups.

Our Professional Approach to Boxelder Beetle Control

 Thorough Inspection

Identifying entry points, congregation areas, and vulnerable structural gaps.

 Targeted Insecticide Treatments

Application of safe, effective products on exterior walls, around windows, doors, soffits, and other access points.

 Exclusion & Sealing Services

Sealing cracks, gaps, and installing physical barriers to prevent future invasions.

 Long-Term Prevention

Recommendations for vegetation management, building maintenance, and ongoing monitoring to keep boxelder beetles out.