The boxelder bug (Boisea trivittata) is a true bug in the seed bug family that feeds almost exclusively on the seeds of boxelder trees (Acer negundo) and, to a lesser degree, silver maple and ash. In summer the insects are rarely noticed — they feed and reproduce in the canopy of host trees without much visibility. As temperatures drop in fall, the adults begin aggregating in sunny, warm locations — south and west-facing walls collect the most solar radiation and draw the highest concentrations — and then move into any available void: attics, wall spaces, window frame gaps, and the interior of the structure.
The Boxelder Tree Connection
Understanding boxelder bug problems requires understanding boxelder trees. Acer negundo is one of the most aggressively self-seeding trees in Missouri — it colonizes fence lines, creek banks, disturbed soil, and the edges of maintained landscapes with remarkable speed, and many homeowners have a boxelder tree on or adjacent to their property without knowing it. The female trees (boxelder is dioecious — male and female trees are separate individuals) produce the winged seed clusters that support bug populations; male trees produce no seeds and attract very few boxelder bugs.
Identifying Boxelder Trees on Your Property
- Compound leaves with 3–5 leaflets (unlike other maples' simple leaves)
- Paired winged seeds (samaras) in clusters — same shape as maple keys
- Common along fence lines, creek edges, disturbed soil margins
- Fast-growing with somewhat weedy character compared to ornamental maples
- Female trees are the seed producers that sustain bug populations
What Actually Works
The most permanent solution to a chronic boxelder bug problem is removing female boxelder trees within 200 feet of the structure and replacing them with non-host species. This is a multi-year fix — existing populations persist for a season or two after tree removal — but eliminates the breeding source rather than managing a symptom. Where tree removal is impractical, exterior perimeter treatment with a residual insecticide in mid-September, combined with structural exclusion of wall void and attic entry points, provides effective season-long suppression. D&D Pest Control handles perimeter treatment and exclusion assessment for rural Missouri and the I-44 corridor — visit ddpestcontrolmo.com.