Here's how to keep them outside where they belong, and avoid the messy stains they leave behind if you squish them.

By Andrea Beck
November 01, 2019
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As the weather cools off in fall, boxelder bugs start bedeviling us in our homes across the country. Perhaps you've spotted a few of these black-and-red insects crawling across your carpet or making its way along the wall and wondered what they are. Boxelder bugs are mostly harmless as far as indoor pests go, but that doesn’t make them any less of a nuisance when they sneak their way inside to spend the winter in a warm spot. Make your house a boxelder bug-free zone this winter with these tips for getting rid of them and keeping them out. Plus, we'll share a few facts about them that can help you combat these little pests.

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1. They Feed on Boxelder Trees

This might be an obvious piece of info given their name, but boxelder bugs love their namesake boxelder trees, which are a type of maple native to North America. The insects primarily eat the clusters of seeds produced by female boxelder trees, but they can feed on the leaves, too. Boxelder bugs may also munch on similar tree species, like others in the maple family and ashes. On some occasions, they’ve been known to feast on fruit and nut trees as well, particularly in western states like California, Nevada, and Texas. Luckily, their appetites are limited to plants—if any of them spend the winter in your house, they won't cause any structural damage.

2. The Critters Love the Sun and Warmth

Bad news for anyone with south- or east-facing windows: boxelder bugs love to hang out in these warm, sunny spaces. If you have windows that let in a lot of light during the fall or winter, don’t be surprised if you come across boxelder bugs nearby. Though they don't hibernate, they slow down when it gets really cold and become more active as temperatures rise. Sometimes turning up the heat in your house during the winter can even trick them into thinking its spring, so they'll come out of hiding.

3. They Can Show Up in Swarms

Like their fellow fall pest, the brown marmorated stink bug, boxelder bugs can show up in large swarms a few times a year. They release a chemical that's undetectable to humans but attracts their black-and-red friends. As the group grows, they will huddle close together while seeking warmth—it’s not uncommon for hundreds to shelter together on a sunny exterior wall of a house or building. Then in the spring, you might see them congregating again as they leave behind their winter shelters and return to the trees. While it might be a creepy sight to behold, the swarms will naturally disappear after a week or two in either season.

4. Squashing Boxelder Bugs Can Leave Stains (And They Stink, Too)

We know it’s tempting to just squash these pests when you spot them in your house, but that can cause more problems you don't want to deal with. When squished, their orange-ish innards can leak out and leave stains on your walls, carpet, and flooring (disgusting, we know). Boxelder bugs can also release a foul smell when they’re squashed or otherwise disturbed, which is even more reason to avoid crushing them. That odor helps them avoid predators outdoors, but it’s unpleasant to have lingering in your living room.

5. These Insects Have Developed a Resistance to Pesticides

According to the U.S. Department of Agriculture, using pesticides against these insects should be considered a last resort, because, over time, boxelder bugs have developed a resistance to many common formulas. That means you won't have much success using insecticides against them. If you’re only seeing a small number of boxelder bugs around your home and garden, stick to the chemical-free ways to deal with them that we suggest below.

How to Get Rid of Boxelder Bugs

The best way to defend your home against boxelder bugs is to prevent them from coming inside in the first place. If you haven’t already, make sure to weather-strip your doors and windows, and seal up any other obvious cracks or holes you find on the outside of your home, like torn window screens and openings around vents. Boxelder bugs aren’t very big, so you won’t be able to completely seal your house against them, but blocking off a few obvious entry points can help reduce the number that come inside.

If boxelder bugs are usually a problem for you in the colder months, you might also want to check out the trees near your house. The seed-bearing female boxelder trees are a big draw for these insects, so if you’ve got one or more in your yard, you could replace it with a tree that’s less attractive to these pests. However, according to the University of Idaho, this may only slightly reduce their numbers—the adults can travel a long way, so even a boxelder tree hundreds of yards away could host bugs that find their way to your house. Raking and disposing of the seeds that appear in spring could help cut down on the problem, though, because young boxelder bugs typically survive on fallen seeds early in the year.

Once you start spotting boxelder bugs inside your house, you’ve got a few options for getting rid of them that don’t involve squashing. Vacuuming them up or sweeping them back outside can help reduce indoor populations. A shop-vac, like the Shop-Vac 4-Gallon All Around Wet/Dry Vacuum, $59.99, Walmart, could even work outdoors if you spot a cluster on the side of your house. It can also make reaching boxelder bugs hanging out on the ceiling or near the top of your walls easier to catch. Just make to sure empty your vacuum into a sealed bag right away, in case any of the bugs survived the trip and try to crawl out.

Simple sprays made with soap and water can also be fatal to boxelder bugs. Add a tablespoon or so of dish washing liquid soap to a spray bottle full of water, and spray the mixture directly on any bugs you see. If it’s possible, you can also try knocking the insects into a bucket of soapy water, where they’ll drown.

Related: 5 Things You Didn't Know About Spider Crickets (And How to Get Rid of Them)

Ultimately, boxelder bugs are harmless, but they can be annoying when they're all over your home. By following these tips, boxelder bugs can be more manageable this fall and winter. Rather than squashing them (avoid those yucky stains and that nose-wrinkling smell), seal your house as best you can to keep them outside. For those that make it inside, a quick vacuum session or a squirt of a soap and water spray can do the trick.

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