Boxelder bugs often gather on sunny exterior walls and slip through gaps to overwinter. The most durable control is blocking entry before large numbers settle into wall and window voids.
Find where they cluster outside
Inspect frames, eaves, siding, and penetrations around pipes or cables. Exterior clusters show where screens, weatherstripping, and gaps deserve attention.
Seal before seasonal entry
Exclusion works best before insects have already moved into cavities. Repair screens and accessible gaps without blocking vents that are designed to remain open.
Remove indoor bugs without crushing them
Vacuum them or collect them in a container. Crushing them can leave odor or stains and does not stop others from emerging from nearby voids.
Avoid whole-home treatment for a few indoor bugs
These bugs generally do not establish a breeding infestation inside the home. If large numbers enter every season, focus on exterior exclusion or arrange a targeted inspection.