Remove boxelder trees and female seed-bearing trees near the house if possible
Trim or replace boxelder, maple, and ash trees that attract them
Seal cracks, gaps, and openings around windows, doors, siding, vents, and foundations
Repair damaged screens and weather stripping
Reduce outdoor lighting at night or switch to yellow bug lights
Use a strong spray of water to knock bugs off walls, trees, and siding
Vacuum up clusters of bugs from exterior surfaces
Apply insecticidal soap or a labeled outdoor insecticide to resting areas
Treat sunny south- and west-facing walls where they gather
Keep grass, weeds, and leaf litter trimmed and cleared away from the house
Rake up and remove fallen boxelder seeds and debris
Store firewood, mulch, and yard clutter away from the home
Use sticky traps outdoors near entry points
Call a licensed pest control professional for heavy infestations