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Box elder bugs in the house: how to get rid of them
Updated 2026-10-31. Advice comes from university extension sources (read on 2026-10-31); items marked Wrenly suggestion are our own advice as a cleaning service. Prices come from our live price list. Disclosure: Wrenly Home sells house cleaning in the Peoria, IL area. We are not a pest control company.
Short answer: boxelder bugs (black, about half an inch long, with red or orange markings) move onto warm south- and west-facing walls in the fall and some squeeze inside to spend the winter[1]. They can't bite or sting[4], don't breed indoors[2] and don't damage the house[3][5]. Vacuum them up rather than crushing them, since crushed bugs smell and their droppings can stain walls and curtains[2][5]; put them in soapy water and throw them away[1]. Indoor sprays generally don't help[1][3]. To prevent next fall's wave, seal gaps before the end of August[2].
What they are, and why they come in
Boxelder bugs (Boisea trivittatus) are "true bugs", related to stink bugs and cicadas[2]. Adults are about half an inch long and black with orange or red markings[1]; the young (nymphs) are smaller, wingless and bright red[4][5]. In spring and summer they feed on the leaves and seeds of boxelder trees and occasionally maple and ash[1], without doing the trees appreciable harm[4].
When fall temperatures drop, they look for a warm place to spend the winter. Illinois Extension says they are most attracted to buildings with large southern or western exposures, because those walls are warmer than their surroundings; they cluster on the wall, find cracks to squeeze into, and some end up in walls and attics until warm weather returns[1]. Buildings that stand taller than their neighbors or alone on flat ground draw more of them; the color of the house doesn't matter[2]. Some years are much worse than others: they are most abundant after hot, dry summers that followed warm springs[2][5].
How to get rid of them indoors
| Step | What to do | Source |
|---|---|---|
| Vacuum them up | Once boxelder bugs are inside, physical removal is the only practical control: a vacuum, or a broom and dust pan. | Minnesota Extension[2]; Iowa State[3]; Purdue[4] |
| Don't crush them | They give off a bad odor when crushed, and their droppings can stain walls, curtains and other surfaces. A vacuum avoids both. | Minnesota Extension[2]; Ohio State[5] |
| Drop them in soapy water | Illinois Extension's advice: vacuum them up, put them in soapy water and throw them away. Empty the canister or bag soon so dead bugs don't smell. (Wrenly suggestion for the timing) | Illinois Extension[1] |
| Skip indoor sprays and bug bombs | Insecticides indoors are generally not recommended. Iowa State says flying-insect aerosols generally don't kill them and "ant and roach" residual sprays haven't been shown to help; Minnesota notes they only live a few days once active indoors anyway. | Illinois Extension[1]; Iowa State[3]; Minnesota Extension[2] |
| Check windows and houseplants | Active bugs head for windows and sunny spots, and they gather around houseplants looking for water. Those are the places to check and vacuum on warm spells. (Wrenly suggestion for the routine) | Minnesota Extension[2] |
It's not practical to treat wall voids and other hiding places to keep them from coming out[2], so indoors the job is simply to keep removing the ones that appear until the season ends.
Stains and smell
Boxelder bugs don't damage furnishings[4], but they can stain walls, curtains and other surfaces with their excrement[2][5], and they release a bad odor when crushed[2]. Vacuuming instead of swatting avoids most of both. For spots that do appear:
- Painted walls and trim: blot the spot (don't rub) with a soft cloth and a little dish soap in water, rinse with a clean damp cloth, and test a hidden spot first. (Wrenly suggestion; we found no extension guidance specific to these stains)
- Curtains and washable fabric: wash as the care label says, and check the spot is gone before drying, since heat can set a stain. (Wrenly suggestion)
- Window sills and tracks: vacuum the dead bugs out of the tracks first, then wipe with a damp cloth. (Wrenly suggestion)
Why they show up in winter
During the coldest weather the bugs stay inactive in their hiding places. On mild, sunny days the warmth wakes some of them and they follow it into the living areas, heading for windows and sunny spots[2]; Iowa State notes furnace heat can do the same[3]. Once active they live only a few days to a week[2]. More come out on warm days in late winter and spring as they try to leave[4][2], and Ohio State puts their departure outdoors around the last week of March[5]. Every one you see indoors got in the fall before; spraying in spring does not stop more from appearing[2].
Keeping them out next year
Every source agrees that keeping them out works best[1][2][3]. Minnesota Extension says to finish repairs before the end of August[2]:
- Make windows and doors fit tight; repair or replace damaged window and door screens (Illinois Extension[1]; Minnesota Extension[2])
- Repair screens in roof and soffit vents and in bathroom and kitchen fans (Minnesota Extension[2])
- Seal where cables, utility wires, pipes, outdoor faucets and dryer vents enter the house, with caulk or, for larger gaps, expanding foam or copper mesh (Minnesota Extension[2])
- Install door sweeps or thresholds on all exterior doors, and a rubber seal along the bottom of the garage door (Minnesota Extension[2])
- Seal cracks around the foundation and chimney, and keep siding, eaves and soffits in good condition (Illinois Extension[1])
- Check attic and crawl-space entries, which can be staging areas for bugs to spread into the rest of the house later (Purdue[4])
- Clear boards, rocks, leaves and other debris from a 6- to 10-foot strip along the foundation, especially on the south and west sides (Ohio State[5])
On the outside of the house
Bugs massing on siding and the foundation can be sprayed with soapy water (Iowa State suggests 5 tablespoons of liquid detergent per gallon of water), repeated as more arrive[3]; Purdue says hot water (165°F to 180°F) applied directly to clusters kills them[4]. Perimeter insecticides are an option, best timed for late summer and early fall when the bugs first gather, but they are hard to make work because the bugs are so mobile[1][2]. Cutting down boxelder trees is generally not recommended, since bugs fly in from elsewhere in the neighborhood[4]. If you use any insecticide, read and follow the label[4]. For help identifying a bug, the University of Illinois Extension office serving Peoria County is at 4810 N. Sheridan Rd., Peoria (309-685-3140)[6].
Are they harmful?
To people, no: boxelder bugs cannot bite or sting[4], are harmless and not disease bearing[3], and are not known to bite humans or animals[5]. They don't damage the house, its furnishings, clothing or food[3][5]. We found no extension guidance about pets eating them; if a pet eats a lot of them or seems unwell, ask your veterinarian (Wrenly suggestion).
What a Wrenly clean covers
We clean; we don't do pest control. Dead or stray boxelder bugs on floors and sills are vacuumed up with the dust on any visit, and a deep clean adds window tracks, blinds, vents and ceiling fans within reach of a two-step stool (see the deep cleaning checklist). We don't spray, seal entry points or work in attics, wall voids or crawl spaces. A large infestation is a job for a pest control company first; book the clean after. If something on the checklist is missed, tell us within 48 hours under our re-clean guarantee.
What it costs
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| Home | Deep clean | Then every 2 weeks (optional) |
|---|---|---|
| Studio / 1 bed (1 bath incl.) | $228 | $155 |
| 2 bed (2 baths incl.) | $272 | $189 |
| 3 bed (2 baths incl.) | $350 | $233 |
| 4 bed (3 baths incl.) | $441 | $306 |
| 5 bed (3 baths incl.) | $558 | $337 |
| Each extra bathroom | +$33 | +$20 |
Book online with your bedrooms, bathrooms and preferred day; we confirm the date by email within one business day.
Frequently asked questions
Why are there box elder bugs in my house?
In fall, boxelder bugs leave the trees they fed on all summer (boxelder, and sometimes maple and ash) and look for a warm place to spend the winter. Illinois Extension says they are most attracted to buildings with large south- or west-facing walls because those are warmer; they squeeze into cracks and some end up in walls and attics, and from there in the living space.
Are box elder bugs harmful to humans?
No. Purdue Extension says they cannot bite or sting, Iowa State calls them harmless and not disease bearing, and Ohio State says they are not known to bite people or animals and don't damage buildings, clothing or food. They are a nuisance: they smell when crushed and their droppings can stain walls and curtains.
Are box elder bugs harmful to cats and dogs?
Ohio State Extension says they are not known to bite humans or animals. We found no extension guidance about pets eating them, so if a pet eats a lot of them or seems unwell, call your veterinarian.
Do box elder bugs lay eggs or breed in the house?
No. Minnesota Extension says they do not reproduce inside: every boxelder bug you see indoors in winter and spring got in the previous fall. Outdoors, eggs are laid on trees in spring.
Why do I see box elder bugs in the house during winter?
They spend the cold months inactive in walls and attics. On mild, sunny days the warmth wakes some of them and they follow it into rooms and to windows; Minnesota Extension says individuals then live only a few days to a week. More appear on warm days into spring as they try to get outside.
How do I get rid of box elder bugs in the house?
Vacuum them up (or use a broom and dust pan), put them in soapy water and throw them away. Indoor insecticides are generally not recommended and aerosols generally don't kill them. To stop next year's wave, seal the gaps they come through before the end of August.
How do I keep box elder bugs out of my house?
Seal them out. Extension guidance: make windows and doors fit tight, repair window, door, soffit, roof-vent and fan screens, seal around pipes, wires, outdoor faucets and dryer vents, add door sweeps and a rubber seal under the garage door, and keep siding, eaves and soffits in good repair. Minnesota Extension says to finish repairs before the end of August.
Does Wrenly Home get rid of box elder bugs?
We clean; we don't do pest control. Dead or stray bugs on floors and sills are vacuumed up with the dust on any visit, and a deep clean also does window tracks, blinds, vents and ceiling fans within reach. We don't spray, seal entry points or work in attics or wall voids; for a large infestation call a pest control company first.
Sources
- University of Illinois Extension, news release: Fall house guests (Ken Johnson, Sep 23, 2019). https://extension.illinois.edu/news-releases/fall-house-guests. Accessed 2026-10-31.
- University of Minnesota Extension: Boxelder bugs (Jeffrey Hahn and Mark Ascerno, entomologists). https://extension.umn.edu/nuisance-insects/boxelder-bugs. Accessed 2026-10-31.
- Iowa State University Extension and Outreach, AnswerLine: What to do about boxelder bugs (Apr 21, 2014). https://blogs.extension.iastate.edu/answerline/2014/04/21/what-to-do-about-boxelder-bugs/. Accessed 2026-10-31.
- Purdue Extension Entomology, E-24: Boxelder Bugs (Timothy J. Gibb, Feb 2018). https://www.extension.entm.purdue.edu/publications/E-24/E-24.html. Accessed 2026-10-31.
- Ohio State University CFAES, HYG-2106: Boxelder Bugs and Leaf-footed Bugs (Mar 9, 2010). https://cfaes.osu.edu/fact-sheet/boxelder-bugs-and-leaf-footed-bugs. Accessed 2026-10-31.
- University of Illinois Extension, unit serving Fulton, Mason, Peoria and Tazewell Counties (offices and contacts). https://extension.illinois.edu/fmpt. Accessed 2026-10-31.
General home-care information drawn from the sources above, not pest-control or veterinary advice. If you use any insecticide, read and follow the label. If anything here is out of date, email [email protected] and we'll correct it.