9 Questions About Boxelder Bugs

Boxelder Bugs
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While entomologists may find these red and black bugs attractive, the average homeowner probably wouldn't be happy to find that boxelder bugs have invaded their home. Although they don't cause damage and aren't dangerous, few people enjoy having large insects crawling out of cracks and onto their walls, windows, lights, or furniture.

If you've ever had boxelder bugs invade your home, you've probably sought information on their identification and control. Here are some of the typical questions pertaining to this common insect and how to control it.

How Do I Identify a Boxelder Bug?

At about a 1/2-inch long, boxelder bugs (Boisea trivittata) have narrow black bodies with red edge lines on their trunk and red lines on the edges of their wings. These markings make it appear as though its wings form an upside-down V when they are lying flat. They are avid flyers and can often travel for several miles at a time.

Why Are Boxelder Bugs Coming Into My Home?

As their name implies, boxelder bugs are attracted to boxelder trees, as well as silver maple trees. If you have either of these trees around your home or in your neighborhood, it's likely that you'll spot boxelder bugs at some point. As soon as the cooler weather hits in the fall, boxelder bugs begin to seek shelter for the winter and are often attracted to the warm, sunny sides of homes. From there, they slip into cracks and gaps in the siding or around doors and windows and can end up seeking shelter inside the home during the winter.

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What Happens if I Don't Get Rid of Them?

If not treated, boxelder bugs will spend the winter months in the walls of your home until warmth brings them out. That warmth doesn't have to mean the spring or summer months—it can actually be heated air from inside your home that coaxes them out of the walls and into the rooms of your home during winter. Like other bugs (such as stink bugs and squash bugs), boxelder bugs can detect temperature differences of as little as one degree, so it doesn't take much for them to decide it's time to move further into a warmer environment.

Are Boxelder Bugs Dangerous?

No. The good news is that boxelders bugs are not harmful to humans or pets and do not sting or bite.

Can Boxelder Bugs Damage the Foliage on Trees?

Boxelder bugs live and breed in boxelder and silver maple trees and feed on the leaves, flowers, and seed pods. However, they are not known to cause any long-term damage, such as killing off a tree or causing disease. In the home, boxelder bugs may end up in your houseplants in search of moisture but aren't likely to cause harm to them either.

Do Boxelder Bugs Cause Any Other Damage? 

They do not cause damage unless they are concentrated in extremely high populations. Boxelder bugs are primarily a nuisance pest—they only live for a few days and do not infest food or cause property damage. While they do not breed indoors, they can be very intrusive and annoying, and their excrement can stain surfaces such as walls, furniture, and drapes.

How Do I Get Rid of Boxelder Bugs?

Once the insects get in, physical removal is the best (and most practical) way to get rid of them. To do so, you have a few options. First, you can use a vacuum with a long hose attachment to gather up the bugs, emptying the canister far from your home's exterior once done. Another option is to spray the bugs with a combination of two parts water to one part dish soap, which can kill the bugs on contact. One thing to keep in mind: Never squash a boxelder bug—you can stain the surface on which you kill it.

How Do I Keep Boxelder Bugs Out of My Home?

To prevent boxelder bugs from entering your home in the first place, consider treating the exterior walls of your home with a residual insecticide. It's most effectively sprayed in the spring or fall when the boxelder bugs are just beginning to emerge (spring) or shelter (fall). The residual will help to deter the bugs from landing on your home, but it will not remain effective once the cold weather sets in. There are also products labeled specifically for boxelder bug control—be sure to read and follow all label instructions and use safety equipment. 

As a general rule of thumb, the best means of prevention is to inspect your home for ways these bugs (and other pests) can be getting in. Add caulk to all cracks, crevices, gaps, and openings in your home. Repair any torn or broken door or window screens, ensure doors and windows are well-sealed, and employ other exclusion techniques to reduce entry points and numbers.

Are There Any Ways to Permanently Keep the Bugs Away?

The most permanent method of controlling boxelder bugs is to remove any boxelder or silver maple trees near the home, as these are the source of food and place of breeding for the bugs. However, this extreme method is not always possible (or warranted) and should be a final option if all other methods fail.