How to Keep Boxelder Bugs Out of Your Home

Boxelder bugs are a common nuisance pest found across North America. As their name suggests, they are often found congregating on boxelder trees, but they will also invade homes, garages, and other structures looking for warmth or food. Getting rid of boxelder bugs can be challenging, but there are steps you can take to keep them from invading your home.

What Are Boxelder Bugs?

Boxelder bugs (Boisea trivittata) are insects that get their common name from their tendency to gather on boxelder trees. They are about 1/2 inch long and black in color with orange or red markings on their body and wings.

Despite their name, boxelder bugs don’t actually feed on or damage boxelder trees. They are sap-sucking insects that use their piercing mouthparts to feed on juices from trees, plants, and sometimes fruits. Their preferred host is female boxelder trees, which produce seeds that the bugs feed on.

Boxelder bugs are a nuisance pest because they congregate in large numbers around structures in the fall seeking protected overwintering sites. They don’t pose any structural or health risks, but their presence in large numbers can be disturbing. Boxelder bugs don’t bite, but they can leave behind red stains if crushed.

Why Boxelder Bugs Invade Homes

Boxelder bugs are looking for warm, dry places to spend the winter. As days grow shorter in late summer and temperatures start dropping in fall, they begin moving to protected sites, often around or inside manmade structures.

Common overwintering sites for boxelder bugs include:

  • Cracks and crevices – Boxelder bugs will squeeze into any narrow space, such as gaps around windows, doors, siding, utility pipes, etc.
  • Attics and wall voids – They readily crawl into attics and hollow walls through small exterior openings.
  • Firewood – Boxelder bugs commonly gather under bark or in crevices of stored firewood. When brought indoors, they become active in living spaces as they warm up.
  • Leaf litter – Aggregations of fallen leaves near foundations provide insulation that attracts overwintering bugs.
  • South and west facing walls – These warmer areas of homes attract bugs looking for heat.

Signs of Boxelder Bug Infestation

The most obvious sign of boxelders is seeing large numbers of the bugs on exterior walls or surfaces. But there are other clues that indicate boxelder bugs have moved into your home:

  • Clusters of bugs around window and door frames.
  • Boxelder bugs crawling on interior walls, curtains, or congregating on ceilings.
  • Red or black streaks on walls or windows from crushed boxelder bugs.
  • Boxelder bug odor from crushed insects. It has a mildly unpleasant, herbaceous smell.
  • Boxelder bug excrement that appears as small dark spots on walls, curtains, or underneath aggregation sites.
  • Dead boxelder bugs around window sills, window frames, curtains, and on the floor under walls where they congregate. Vacuuming them up daily can help track the severity of an infestation.

How to Keep Boxelder Bugs Out of Your Home

Keeping boxelder bugs from invading your home involves diligence, thoroughness, and persistence. Their small size enables them to exploit even tiny cracks and openings. Fortifying your home’s exterior and being vigilant about monitoring and removal are key prevention steps.

Seal Cracks and Openings

The most important exclusion tactic is caulking, sealing, screening, or otherwise blocking potential entry points around your home’s exterior. Pay particular attention to:

  • Windows – Caulk or seal gaps around frames. Ensure window sashes seal tightly when closed. Install tight-fitting screens.
  • Doors – Weatherstrip and install door sweeps to seal the gap between the door and threshold. Keep exterior doors shut as much as possible in fall.
  • Siding – Seal any cracks, gaps, or holes in siding with caulk. Pay special attention around utility pipes, wires, fixtures, and vents.
  • Attic vents – Seal areas around vents with stainless steel mesh screening or hardware cloth.
  • Chimneys – Install a chimney cap and seal open masonry joints with mortar.
  • ** Foundation** – Seal any cracks or gaps around the foundation with caulk or expandable foam. Install door sweeps on basement or crawl space access doors.

Remove Boxelder Bug Entry Points

In addition to sealing up cracks, also modify or remove potential entryways:

  • Trim back vegetation and branches touching the home’s exterior.
  • Move firewood and leaf litter piles away from the foundation.
  • Clean gutters and downspouts regularly to allow proper drainage.
  • Ensure attic and crawl space vents are cleared of debris.
  • Install tight-fitting covers or screening over window wells.
  • Replace loose fitting screens.

Inspect Your Home’s Exterior

Canvas your home’s exterior at least weekly in fall, looking for potential entry points and signs of invading bugs. Target your inspection on southern and western facing walls and around potential problem areas like vents, windows, doors, etc.

Catching and sealing off entryways early, before bugs have a chance to establish themselves inside, is important. Use a flashlight and magnifying glass if needed to spot the small insects and tiny cracks.

Vacuum Indoors

If boxelder bugs have found their way inside, regularly vacuuming up the insects can help reduce their numbers. This is especially important in fall as bugs come indoors seeking warmth.

Focus vacuum efforts near windows, around door frames, on ceilings, and wherever you see aggregations of boxelder bugs. Remove and dispose of the vacuum bag promptly after use.

Remove Indoor Clutter

Boxelder bugs search out protected spaces to overwinter, and indoor clutter provides attractive hiding spots for them. Keeping your home tidy and organized denies them safe harbor:

  • Store seldom used items in sealed plastic or glass containers.
  • Remove stacks of newspapers, magazines, cardboard boxes, etc.
  • Clean out storage areas and attics to eliminate clutter.
  • Move indoor plants away from windows and doors.
  • Eliminate hiding places like piles of drapes, blankets, clothing, etc.

Use Exclusion Lighting

Installing yellow “bug” lights around entry points may help deter some boxelder bugs from entering, as they are less attracted to the yellow wavelength of light. Use them around doors, garage doors, patio doors, and other key areas.

Employ Pest Control Measures

For severe infestations, pesticide sprays applied around a home’s exterior in strategic areas in early fall can help reduce bug entry. However in most cases diligent exclusion and vacuuming are sufficient.

Indoor chemical control carries risks and limited effectiveness. Any pesticides should only be applied by a licensed professional. Avoid “bug bomb” total release foggers, as they cannot penetrate boxelder bug hiding places.

Tips for Keeping Boxelder Bugs Off Trees

Sealing up your home’s exterior is the best defense, but minimizing bugs on nearby female boxelder trees can also help reduce migration to your home.

  • Regularly trim branches touching structures. This eliminates “bug bridges”.
  • Encourage natural predators like birds that eat boxelder bugs by installing bat houses and maintaining healthy bird habitat.
  • Apply sticky barrier bands around tree trunks to trap migrating bugs.
  • Spray tree trunks with vegetable oil in fall to make it harder for bugs to climb up.
  • In severe cases, pesticide application to female boxelder trees may be warranted. Hire a licensed arborist.
  • As a last resort, remove severely infested female boxelder trees.

When to Call a Professional Exterminator

Most boxelder bug situations can be self-managed through diligent exclusion and vacuuming. But if all your prevention efforts fail to stop an indoor infestation, it may be prudent to have a professional pest control company assess your home.

Signs it may be time to call in an exterminator include:

  • Boxelder bugs appearing regularly in large numbers indoors despite your exclusion and sanitation efforts.
  • Bugs emerging from cracks inside walls or ceilings. This indicates they have established nesting sites inside voids.
  • An influx of boxelder bugs via non-obvious entry points you cannot locate or seal.
  • Discovering significant indoor boxelder bug aggregations in out-of-reach areas like inside wall voids, attics, crawlspaces, etc.
  • You have health concerns about crushing large numbers of bugs or the nuisance has become intolerable.

Look for licensed pest control companies experienced in boxelder bug exclusion and eradication. Fumigation or heat treatments may be required for severe infestations inside wall voids.

Preventing Boxelder Bugs Year-Round

Keeping boxelder bugs out requires diligence beyond just the fall months when they are most active. Ongoing maintenance and monitoring is important:

  • In spring, repair any winter damage to seals, caulk, screening etc. before bugs become active.
  • Keep vegetation trimmed back from the home’s exterior year-round.
  • Maintain tidy indoor spaces all year, eliminating bug hiding spots.
  • Check for boxelder bug activity on female trees in summer and take steps to discourage infestations.
  • Monitor for early signs of bugs in August and September and take action. Don’t wait for heavy fall infestations before excluding them.
  • Continue exclusion techniques like sealing, caulking, lighting, and cleaning throughout fall until cooler temperatures halt bug activity.

With vigilant prevention and monitoring, boxelder bugs don’t have to become a nuisance each fall. Don’t let them ruin your enjoyment of the season.

Frequently Asked Questions About Boxelder Bugs

How do boxelder bugs get inside my home?

Boxelder bugs enter homes through cracks around windows, doors, siding, attic vents, and anywhere else they can squeeze through. Sealing these entry points is the best way to block them.

Will boxelder bugs infest my pantry or food?

Boxelder bugs are not typically pantry pests. They prefer overwintering sites, not food items. But it’s still wise to keep them out of pantries and kitchens.

Do boxelder bugs pose dangers to pets or humans?

Boxelder bugs don’t bite or spread disease. They are harmless to humans and pets, but their nuisance presence and staining make them undesirable house guests.

What attracts boxelder bugs to my home?

Boxelder bugs are attracted to the warmth, shelter, and hiding places homes provide as they seek protected sites to overwinter. South or west facing walls tend to attract them most.

How can I get rid of boxelder bugs in my house?

Vacuuming and exclusion techniques like sealing cracks are the safest ways to eliminate indoor boxelder bugs. Avoid pesticide foggers or sprays indoors. Professional extermination may be needed for severe infestations inside walls or attics.

What season do boxelder bugs come out?

Boxelder bugs are most active in spring and fall. They congregate on trees in summer, then begin migrating to overwintering sites in late summer and peak fall seasons as temperatures drop.

Why are there so many boxelder bugs this year?

Mild winters and wet springs contribute to larger boxelder bug populations in a given year. Their numbers naturally fluctuate year-to-year. Large infestations are cyclical.

Are boxelder bugs harmful to my trees or plants?

Boxelder bugs feed on sap and don’t directly damage most plants. But heavy infestations can sometimes stress trees. Their presence alone doesn’t necessitate pesticide treatment.

What’s the best pesticide for boxelder bugs?

For homes, exclusion and vacuuming are recommended over pesticides. If chemical control is needed, hire a licensed professional to target bugs outside only. Avoid total release foggers/bug bombs.


Boxelder bugs can be a challenging nuisance to deal with each fall, but a little prevention and persistence goes a long way. Focus on sealing up potential entry points on your home’s exterior early in the season before bugs congregate. Continue monitoring and actively vacuuming any invaders that make it inside. Maintaining a tidy, clutter-free home eliminates attractive hiding spots indoors. With diligence, boxelder bugs don’t have to take over your home each autumn.