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Boxelder bugs show up in fall when they’re looking for warm places to spend winter. They don’t bite or cause structural damage, but they stain surfaces when crushed and nobody wants hundreds of them clustering on sunny walls. Here’s how to get them out and keep them out.
1. Seal Entry Points
Find where they’re getting in. Check window frames, door thresholds, foundation cracks, utility penetrations, and anywhere siding meets trim. Boxelder bugs squeeze through gaps you wouldn’t think possible. Use caulk for small cracks and expanding foam for larger gaps. Pay attention to south and west-facing walls since those get afternoon sun and that’s where boxelder bugs congregate.
2. Vacuum Them Up
For bugs already inside, a vacuum works better than squashing them (which leaves red stains). Use the hose attachment and empty the bag or canister immediately after. If you leave them in there, some will crawl back out. Dispose of the bag outside or dump the canister into a sealed plastic bag.
3. Dish Soap Spray
Mix 1-2 tablespoons of dish soap per quart of water in a spray bottle. Spray directly on the bugs. The soap breaks down their exoskeleton and they die within minutes. This works on contact but doesn’t have residual effect, so you’ll need to spray each batch you find. Good for clusters on windows or walls.
4. Diatomaceous Earth Barriers
Sprinkle food-grade diatomaceous earth along baseboards, windowsills, and entry points. The microscopic sharp edges cut through the bugs’ protective coating and dehydrate them. Reapply after vacuuming or if it gets wet. Wear a dust mask when applying since it’s irritating to breathe.
5. Remove Host Trees
Boxelder bugs feed on boxelder, maple, and ash trees. If you have female boxelder trees (the ones with seed pods), that’s the source. Removing the tree eliminates the attraction. If removal isn’t an option, keep fallen seeds and leaves cleaned up since bugs feed on those too.
6. Perimeter Insecticide Treatment
Apply residual insecticide around the foundation, focusing on south and west sides where bugs congregate. Do this in late summer before they start moving indoors. Products with bifenthrin or permethrin work. Follow label directions for mixing and application rates. This creates a barrier that kills bugs as they try to enter.
7. Light-Colored Exterior Paint
Boxelder bugs are drawn to dark, warm surfaces. If you’re repainting, lighter colors absorb less heat and attract fewer bugs. This won’t solve an existing problem but reduces future infestations. White or light gray siding stays cooler than dark brown or black.
8. Remove Outdoor Debris
Clean up leaf piles, firewood stacks, and other debris near the foundation. Boxelder bugs overwinter in protected spots and debris gives them places to hide. Store firewood at least 20 feet from the house and elevated off the ground.
You’ll have the best results combining sealing with outdoor population control. Deal with the bugs outside before they get in, then seal up so stragglers can’t follow.