If you’ve noticed black and red bugs clustering on your house each fall, you’re dealing with boxelder bugs. These insects gather in large numbers as temperatures drop, and many find their way inside. When homeowners see dozens or hundreds of these bugs, the first question is: are they dangerous?
The answer is no. Boxelder bugs are not dangerous to people, pets, or property.
Are Boxelder Bugs Dangerous?
Do Boxelder Bugs Sting or Bite?
Boxelder bugs do not bite humans. They lack the mouthparts to break human skin. Unlike mosquitoes, bed bugs, or fleas, they have no interest in feeding on blood.
They also do not sting. Boxelder bugs are not related to wasps, bees, or hornets. They have no stinger and no venom. Even when threatened or trapped, they will not attack.
Some people report a slight prickling sensation if a boxelder bug walks across their skin, but this is simply the bug’s legs, not a bite. The sensation is harmless.
Do They Spread Diseases?
Boxelder bugs are not vectors for disease. They do not carry or transmit illnesses to humans or animals. There are no documented cases of boxelder bugs spreading bacteria, viruses, or parasites. This puts them in a different category from pests like ticks, mosquitoes, and rodents, which can pose real health risks.
Can Boxelder Bugs Damage my Home?
They Don’t Damage Your Home’s Structure
Unlike termites or carpenter ants, boxelder bugs do not eat wood. They will not chew through your walls, floors, or support beams. They cause no structural damage to buildings.
Boxelder bugs feed on seeds from boxelder trees, maple trees, and ash trees. They use their piercing mouthparts to extract fluids from these seeds. Once inside your home, they do not feed at all. They do not reproduce indoors either. They simply wait out the winter in a dormant state.
Your furniture, carpets, clothing, and stored items are safe from boxelder bugs. They have no interest in these materials.
They Don’t Harm Your Garden or Landscape
Boxelder bugs feed on trees, but the damage they cause is minimal. They extract fluids from seeds and occasionally pierce leaves. This feeding does not kill trees or cause significant harm.
Agricultural experts do not classify boxelder bugs as major pests. Farmers do not treat for them because they do not damage crops.
If you have boxelder, maple, or ash trees on your property, you may see boxelder bugs on them during warmer months. The trees will be fine. The bugs are more of a visual nuisance than a threat to plant health.
Why They Enter Homes
Boxelder bugs seek shelter as cold weather approaches. They look for protected places to overwinter. In nature, they hide in tree bark, leaf litter, and rock crevices. Buildings offer protection from wind, precipitation, and predators.
They are attracted to sun-warmed surfaces. South-facing and west-facing walls receive the most sunlight and warmth, which is why boxelder bugs cluster there in fall. They congregate on siding, around windows, and near roof lines.
They enter through surprisingly small openings. Gaps as small as one-eighth of an inch provide entry. Common entry points include:
- Cracks around window and door frames
- Gaps where utility lines enter the building
- Openings around vents and exhaust fans
- Damaged or poorly fitted screens
- Spaces under siding or fascia boards
- Foundation cracks
Buildings near female boxelder trees face the biggest risk. Female boxelder trees produce seeds, which are the bugs’ primary food source. If you have these trees on or near your property, you will likely see more boxelder bugs.
Are Boxelder Bugs Harmful?
While boxelder bugs are not dangerous, they can be a significant nuisance. Here’s what you need to know:
- No bites or stings: Boxelder bugs do not bite, sting, or transmit diseases to humans or pets. You can handle them without risk of being bitten or stung.
- Property damage through staining: They can stain walls, curtains, and furniture with their excrement. These stains are reddish or orange and can be difficult to remove from light-colored surfaces. When hundreds of bugs spend time in one area, the accumulation of waste leaves visible marks.
- Odor issues when crushed: The smell they emit can linger and be unpleasant throughout your home. If you vacuum them up, the odor may remain in your vacuum bag or canister. If you step on them, you may leave marks on floors or carpets.
Once boxelder bugs are inside, they can be hard to eliminate. They hide in wall voids and attics. When indoor heat warms them up, they become active and wander into living areas. You can vacuum them up, but more may appear the next day.
Signs of a Boxelder Bug Infestation
How do you know if you have a boxelder bug problem? Watch for these signs:
- Large groups on exterior walls: Boxelder bugs gather in large numbers on sunny walls, especially during fall. South-facing and west-facing walls receive the most warmth and attract the most bugs.
- Invasion of living spaces: Bugs enter through small cracks and gaps. They often congregate near windows and light sources once inside.
- Unpleasant odor: When crushed, boxelder bugs emit a foul smell that can linger in your home.
Prevention Is Key
The best approach to boxelder bugs is prevention. Since they don’t cause real harm, the goal is simply to keep them outside where they belong.
Seal potential entry points before fall arrives. Use caulk to fill cracks around windows and doors. Install or repair weatherstripping. Add door sweeps to exterior doors. Replace damaged screens. Check where utility lines enter your home and seal any gaps with foam or copper mesh.
Pay attention to the foundation. Walk around your home and look for cracks or openings. Seal them before boxelder bugs start seeking shelter.
If you have female boxelder trees close to your house, consider removing them or replacing them with trees that don’t attract these bugs. This is the most effective long-term solution if you face heavy infestations year after year.
For bugs that are already inside, physical removal works best. Vacuum them up or sweep them into a dustpan and dispose of them outdoors. Do not crush them if you want to avoid stains and odors.
When to Call a Professional
Most homeowners can manage boxelder bugs on their own through exclusion and physical removal. But if you face a large infestation year after year, professional pest control may be worth considering.
Candor Pest Control serves Boise, ID, Nampa, ID, and Ontario, OR. We can apply barrier treatments to the exterior of your home in late summer or early fall. These treatments target bugs as they congregate on exterior walls before entering. The treatments use insecticides labeled for structural pest control and are applied around doors, windows, and siding.
If boxelder bugs are inside your home, we also offer interior treatments to get rid of them.
