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If you’re trying to figure out how to get rid of boxelder bugs, the good news is that they’re harmless, and the fix is mostly about keeping them out. For years I saw a handful of dark bugs scattered around our house every fall and assumed they were roaches. They weren’t. They were boxelder bugs, and once you know what you’re looking at, they’re a lot easier to deal with.
This guide covers how to tell boxelder bugs from roaches, why they come inside in the fall, whether they can hurt you, the 5 steps to get rid of them, why you might still see them on warm winter days, and what doesn’t work.
WHAT’S IN THIS GUIDE
Boxelder Bugs or Roaches? How to Tell
I’m not the only one who’s mixed them up. A dark bug walking across the floor in the fall looks like a roach at a glance, but up close they’re easy to tell apart:
- Boxelder bugs are about 1/2 inch long, black, and flat on top, with bright red or orange lines along the edges of the body and three red stripes right behind the head. Their wings fold flat and make an X shape across the back.
- Roaches are brown or reddish-brown with no red stripes, have long, whip-like antennae, and run fast. They hide from light and usually show up near food, water, and the kitchen.
- They move slowly, often sit out in the open on walls and windows, and gather on the sunny side of the house.
Young boxelder bugs, called nymphs, are smaller and mostly bright red. If you see red and black bugs on a sunny wall or near a window in the fall, they’re almost certainly boxelder bugs. Source: University of Minnesota Extension
Why Boxelder Bugs Come Inside in the Fall
Boxelder bugs spend the summer feeding on boxelder trees, especially the seed-bearing female trees, and sometimes on maples and ash. When the weather cools in the fall, the adults look for a protected place to spend the winter. They gather on the south and west sides of buildings where the sun warms the walls, then crawl into cracks and gaps around windows, doors, siding, and the foundation.
Most of them stay inside the walls all winter. A few find their way into the living space, which is why you see a handful scattered around the house instead of a big cluster. You don’t need a boxelder tree in your yard to get them, either. The adults fly well and can travel several blocks, and sometimes as far as two miles. Source: University of Minnesota Extension
Are Boxelder Bugs Harmful?
Not really. Purdue Extension says boxelder bugs can’t bite or sting, and they don’t damage the house, your furniture, or your food. They also don’t breed indoors, so the handful you see won’t turn into an infestation the way roaches would. The main problem is that they’re a nuisance, and if you crush one, it can leave a stain on walls, curtains, or carpet. Source: Purdue Extension, Whitley County
How to Get Rid of Boxelder Bugs in 5 Steps
Step 1: Vacuum up the ones inside
The best way to get rid of boxelder bugs that are already in the house is to vacuum them up. Don’t swat or squish them, since that’s what causes stains. A shop vac works well for windowsills and corners, and you can empty it outside. Extension experts don’t recommend spraying insecticide indoors once the bugs are inside. Vacuuming is faster, cleaner, and works just as well. Source: University of Minnesota Extension
Step 2: Find where they’re getting in
Walk around the outside of the house on a sunny fall afternoon and look at the south and west walls, where they gather. Check around window frames, door frames, where pipes and wires enter the house, gaps under the siding, and the soffits. Inside, notice which rooms they keep showing up in. That usually points to the closest entry spot.
Step 3: Seal cracks and gaps
This is the step that actually keeps them out. The University of Minnesota recommends sealing openings 1/8 inch or larger. Use a caulk gun and silicone or siliconized latex caulk for small gaps around windows, doors, and trim. For bigger gaps, like where pipes and wires come through the wall, stuff in copper mesh and seal it with expanding foam. Leave the weep holes at the bottom of brick walls open, since those let moisture drain out. Our guide on how to seal windows and doors for winter covers each type of gap. Source: University of Minnesota Extension
Step 4: Fix screens and add door sweeps
Torn window screens and gaps under exterior doors are easy ways in. Patch small tears with a window screen repair kit and add a door sweep to any exterior door where you can see daylight underneath. Check the screens on attic and bathroom vents too. The same fixes keep out stink bugs, mice, and other fall invaders.
Step 5: Knock down clusters outside
If you see them gathering on the outside of the house, you can deal with them before they get in. Purdue Extension says pouring hot water, about 165 to 180°F, directly on a cluster kills them. Use care around plants and don’t do it on hot siding that could be damaged. For homes with a history of heavy invasions, an exterior insecticide labeled for boxelder bugs can be sprayed on the sunny walls in late summer or early fall, when they first start to gather. Spraying is only a supplement to sealing, not a replacement. Source: Purdue Extension, Whitley County
Why You Still See Them in Winter
Boxelder bugs that made it into the walls in the fall don’t die off. On a warm, sunny winter day, the heat wakes them up and some wander out into the house, usually near windows and houseplants. That doesn’t mean new bugs are getting in. They’re the ones that were already inside the walls. Vacuum them up as they appear, and in spring the rest will head back outside on their own. If you see them on the outside of the house in spring, there’s no need to spray. They’re leaving, not coming in. Source: University of Minnesota Extension
What Doesn’t Work
A few common approaches waste time and money:
- Spraying inside the house. Bug spray only kills the few you hit, and treating inside the walls isn’t practical. Vacuuming does the job without the chemicals.
- Cutting down boxelder trees. The University of Minnesota doesn’t recommend it, since the bugs can fly in from trees up to two miles away. You’d lose the tree and still have the bugs.
- Spraying in the spring. By then they’re leaving the house, not entering it.
- Squishing them. It works, but it leaves stains. Vacuum instead.
Source: University of Minnesota Extension
If you’ve had stink bugs this fall too, the prevention is almost identical. See our guide on how to get rid of stink bugs. Sealing gaps also helps you keep mice out of your house, and it’s one of the 15 tasks on our winter home maintenance checklist.
Seeing spiders too this fall? Here’s how to get rid of spiders in the house.
Frequently Asked Questions About Boxelder Bugs
What attracts boxelder bugs to my house?
Warmth and shelter. In the fall, they gather on the sunny south and west sides of houses, then crawl into any cracks or gaps they can find to spend the winter. Homes near boxelder, maple, or ash trees tend to see more of them.
Do boxelder bugs bite?
No. According to Purdue Extension, boxelder bugs can’t bite or sting. They’re harmless to people and pets, and they don’t damage the house.
Do boxelder bugs lay eggs in your house?
No. They don’t reproduce indoors. They lay their eggs on boxelder trees outside in the spring, so the ones you find inside won’t multiply.
How do I get rid of boxelder bugs naturally?
Vacuum up the ones inside, seal the cracks and gaps they use to get in, fix torn screens, and pour hot water on clusters outside. That combination handles most homes without any insecticide.
Are boxelder bugs the same as roaches?
No. Boxelder bugs are black with red or orange stripes and move slowly. Roaches are brown, have long antennae, run fast, and hide near food and water. Roaches breed indoors, but these bugs don’t.
When do boxelder bugs go away?
They head back outside in the spring, around the time trees start to leaf out. Until then, you may see a few on warm winter days. Keep vacuuming them up, and seal any gaps you find so fewer get in next fall.
Sources & Further Reading
- Source: University of Minnesota Extension
- Source: Purdue Extension, Whitley County
- Source: Penn State Extension — Boxelder Bug