How to Get Rid of Boxelder Bugs (Inside and Out)

On a warm fall afternoon, you might notice your home’s sunny walls crawling with black-and-red insects — flat, narrow bugs about half an inch long, clustering by the dozens around windows and doors. Those are boxelder bugs, and like stink bugs, they’re fall invaders looking for a warm place to spend the winter.

Boxelder bugs don’t bite, don’t sting, and don’t damage your home’s structure. But they gather in alarming numbers, sneak indoors through tiny gaps, and — their signature party trick — stain light-colored curtains, walls, and fabrics with their droppings if crushed or left alone. A few dozen on the siding is a nuisance; several hundred inside your walls is a problem worth preventing.

This guide covers how to get rid of boxelder bugs both outside (where the invasion starts) and inside (where the stragglers end up).

Understanding the Enemy: Why Boxelder Bugs Gather

Boxelder bugs feed on boxelder, maple, and ash trees during spring and summer. In fall, as temperatures drop, they seek sheltered overwintering sites — and they have a strong preference for warm, sun-facing surfaces. Your home’s south and west walls, especially light-colored siding, are ideal.

Key facts that shape the strategy:

• They gather in large aggregations — where you see twenty, there are usually hundreds nearby.
• They enter through gaps as small as 1/8 inch around windows, doors, siding, and utility openings.
• Once inside wall voids, they go dormant for winter. Warm spells wake them, and they wander into living spaces.
• They don’t reproduce indoors — every bug inside came from outside this fall.

The takeaway: this is an exclusion battle, not an extermination battle. Stop them at the wall and you win.

Outside: Breaking Up the Gathering

Step 1: Remove what attracts them

• Address the host trees. If you have a female boxelder tree near the house, it’s the root cause — these trees produce the seeds boxelder bugs feed on. You don’t have to cut it down, but know that proximity to one guarantees annual invasions. Rake up and dispose of fallen boxelder seeds in fall.
• Trim branches touching the house — they’re highways to your siding.
• Clear leaf litter and debris from foundation beds where bugs congregate.

Step 2: Hit the clusters with soapy water

For the bugs already massed on your siding, the simplest effective treatment is a dish-soap-and-water spray:

1. Mix 1–2 tablespoons of liquid dish soap per quart of water in a pump sprayer (a garden hose-end sprayer works for high walls).
2. Spray clustered bugs directly and thoroughly — the soap breaks down their protective coating and they dehydrate.
3. Apply on a warm afternoon when bugs are active and gathered.
4. Repeat as new clusters form during the fall invasion period.

This is non-toxic to people and pets, won’t harm your siding, and kills on contact. Its limitation: no residual effect, so it’s a knockdown tool, not a barrier.

Step 3: Apply an exterior barrier treatment

For heavy, recurring invasions, a residual insecticide labeled for boxelder bugs creates a barrier they cross to enter:

• Apply to the sunny exterior walls, focusing on a band around windows, doors, eaves, and the foundation — the routes they use.
• Time it for early to mid-fall, before the peak invasion, and reapply per the label if the season is long.
• Read the entire label first. Keep the product off flowering plants that attract pollinators, away from vegetable gardens, and keep children and pets off treated surfaces until fully dry.
• Never spray near ponds, streams, or storm drains unless the label specifically permits it.

Sealing: Keeping Them Out for Good

No spray replaces sealing. Do this work in late summer or early fall, before the invasion peaks:

• Windows and doors: repair screens, replace worn weatherstripping, caulk gaps between frames and siding.
• Siding: caulk where siding meets trim, corner boards, and around the foundation line. Boxelder bugs love the gap behind loose siding.
• Utility penetrations: seal around outdoor faucets, vents, pipes, and cable entries with caulk or copper mesh.
• Attic vents: screen gable, soffit, and ridge vents with fine mesh — boxelder bugs overwinter happily in attics.
• Door sweeps: install or replace on every exterior door, including the garage-to-house door.

Do your sealing walk on a sunny fall afternoon and watch where the bugs cluster — they’re showing you exactly where the gaps are.

Inside: Dealing With the Ones That Got In

If boxelder bugs are already indoors, remember: they won’t reproduce inside, and the population is finite. Your job is removal, not warfare.

• Vacuum them up — the fastest method for clusters on windowsills and walls. Use a hose attachment and empty the vacuum outside right away.
• Soapy-water jar for stragglers: knock them into dish-soapy water.
• Don’t crush them on light fabrics, curtains, or walls — their bodies leave reddish-brown stains.
• Don’t spray insecticide indoors for boxelder bugs. The ones you see are wanderers from the wall void; spraying them does nothing about the rest, and foggers just coat your home in residue without reaching the bugs.
• Light traps (a lamp over a pan of soapy water, left on overnight in a dark room) catch the confused ones that emerge on warm winter days.

The Long-Term Play: Reducing Next Year’s Invasion

• Keep up the exclusion work — sealed gaps stay sealed for years with occasional touch-ups.
• If a female boxelder tree dominates your yard, consider replacing it with a non-host species. It’s the single biggest long-term reduction you can make.
• Rake and dispose of boxelder/maple seeds each fall rather than mulching them in place.
• Note where they gathered this year and pre-treat or reinforce those spots next August.

Frequently Asked Questions

Do boxelder bugs bite?

No. They don’t bite people or pets, don’t sting, and don’t transmit diseases. They’re purely a nuisance pest.

Will boxelder bugs damage my house?

They don’t eat wood, wiring, or insulation. The only “damage” is staining from crushed bugs or droppings on light surfaces, and the general unpleasantness of hundreds of insects in your walls.

Why are there so many on one side of my house?

They follow warmth. South- and west-facing walls get the most afternoon sun, so that’s where they aggregate — and where your sealing efforts should concentrate.

How long do they stay inside?

They overwinter from roughly October through March, mostly dormant in wall voids. You’ll see wanderers on warm days and a final wave when they emerge in spring to head back outside.

Are boxelder bugs and stink bugs the same thing?

No, but they’re often confused because both invade homes in fall. Boxelder bugs are narrower, black with red-orange edge markings; stink bugs are broader, shield-shaped, and brown. The exclusion strategy is nearly identical for both.

📚 Sources & Further Reading

• NPIC: Minimizing Pesticide Exposure
  Practical tips on choosing lower-toxicity products, protective equipment, and keeping children and pets safe from the National Pesticide Information Center (Oregon State University & U.S. EPA).

🚨 If someone ingests a pesticide or shows poisoning symptoms, call Poison Control immediately: 1-800-222-1222 (U.S.).

Related Guides

• Fall Home Maintenance Checklist — the seasonal sealing walk-around that stops boxelder bugs and other fall invaders.
• Is Pest Control Safe for Pets? — safety guidance for any exterior treatment used around animals.
• Spring Pest Prevention Checklist — handling the spring emergence when overwintering bugs head back out.
• How to Keep Stink Bugs Out of Your House This Fall — keeping stink bugs out.
• Ladybugs Invading Your House? How to Get Them Out (Fall Guide) — dealing with ladybug invasions.
• Fall Pest Prevention Checklist (Free Printable PDF) — the full fall pest-proofing checklist.