Boxelder Bug Infestation

Boxelder Bug Infestations

Homes with a seed-bearing boxelder tree nearby see the most of these bugs. As days get shorter and cooler in fall, adults leave the trees and look for a protected place to spend the winter, slipping behind siding, into wall voids and under window trim. The sides of a house that get the most sun warm up first, which is why they collect there. They stay inactive through the cold months, but a warm afternoon or heat from inside the house can wake them early and send them wandering into living areas.

The harm is small. Boxelder bugs do not carry disease or go after people, and they lay eggs only outdoors on and around host trees, so they do not breed inside. The real complaints are the reddish-orange spots their droppings leave on curtains, walls and fabric, and the sharp smell they give off when crushed or disturbed.

What a Boxelder Bug Problem Looks Like

The most obvious sign is clustering. Adults gather on warm, sunny siding, around window and door frames, on fences and on the trunks of host trees, sometimes by the hundreds. In summer, groups of bright red nymphs can be seen in the grass and leaf litter beneath seed-bearing trees. Indoors, the usual sign is a few slow, sluggish bugs on windowsills, near lamps or on the glass on a warm afternoon in the cooler months.

Places to check outside:

• South- and west-facing walls that catch afternoon sun
• Gaps behind siding, trim and window casings
• The trunk of the host tree and the ground where its seeds collect
• Attic vents, soffits and openings around utility lines

The Florida picture: our mild winters give true boxelder bugs less reason to crowd into homes than they have farther north, so large indoor invasions are far less common here. Many Florida reports turn out to be red-shouldered bugs instead. These bunch together in big, eye-catching groups on the ground, sidewalks, driveways and tree trunks beneath goldenrain trees, especially when seed pods are dropping. They are mainly an outdoor nuisance, though a few may wander inside through open doors or torn screens.

Before deciding what to do, confirm which bug you have on the boxelder bug species page.