How to Get Rid of Boxelder Bugs in Eau Claire: Seal Them Out, Then Vacuum

How to Get Rid of Boxelder Bugs in Eau Claire: The Short Answer

How to get rid of boxelder bugs comes down to timing. Seal the gaps they use to get in before they start gathering on your siding, then vacuum up the ones that make it inside. Spraying the house interior, or the bugs you find crawling across the living room in February, does very little. If you have a big infestation year after year, the pest control companies in Eau Claire in our directory can treat the outside of the house at the right time of year.

Boxelder bugs are about 1/2 inch long, black, with orange or red markings and three stripes just behind the head. University of Minnesota Extension notes they give off a bad smell when crushed.

Are boxelder bugs harmful to people or my house?

Boxelder bugs are harmless to people. The University of Wisconsin Insect Diagnostic Lab calls them completely harmless to humans, and Minnesota Extension says they normally cause no property damage. The real problem is staining: their waste can mark walls, curtains and other light surfaces.

How to Get Rid of Boxelder Bugs Depends on the Season in Western Wisconsin

The UW-Madison Division of Extension lays out the yearly cycle for Wisconsin. Adults lay eggs on trees in spring. A second generation is active in August and September. That second generation is the one that shows up on houses, gathering on the outside walls on sunny days in September and October before moving indoors to spend the winter in attics and wall voids.

Why are boxelder bugs all over my house this year?

Boxelder bug numbers swing with the weather. UW Extension says populations are highest after dry spells, and wet weather spreads a fungal disease that keeps them in check. Minnesota Extension adds that they are most abundant during hot, dry summers that follow warm springs, and that they are not a serious problem every year.

Your house itself matters too. Minnesota Extension found boxelder bugs favor buildings with a lot of southern or western exposure, and buildings that stand taller than their neighbors or sit alone on flat ground. The color of the house makes no difference.

Why do boxelder bugs show up inside in the middle of winter?

Boxelder bugs that wintered in your walls or attic wake up when warmth reaches them. On mild, sunny days they follow that warmth into living areas and head for windows. Minnesota Extension notes that once active indoors they live only a few days up to a week, and that they do not reproduce inside. Every boxelder bug you see in winter and spring got in the fall before.

How to Get Rid of Boxelder Bugs Before They Get Inside

Sealing the house is the most effective step. Minnesota Extension recommends making repairs before the end of August, ahead of the fall gathering. Its checklist:

• Repair or replace damaged window and door screens.
• Repair screens in roof and soffit vents and in bathroom and kitchen fans.
• Seal where cables, phone lines, utility wires, pipes, outdoor faucets and dryer vents enter the house.
• Use caulk for small gaps and polyurethane expanding foam, copper mesh or another suitable sealant for larger spaces.
• Add door sweeps or thresholds to every exterior door, and a rubber seal along the bottom of the garage door.

UW Extension gives the same advice in shorter form: caulk windows and doors and repair window and door screens.

What gaps should I seal on a brick, stone or stucco house?

On brick, stone, stucco or plaster, Minnesota Extension suggests sealing openings 1/8 inch or larger, especially where vertical surfaces meet horizontal ones and where two materials meet, such as brick and wood siding. Silicone, elastomeric latex or silicone/acrylic caulk all work. Do not seal the weep holes at the bottom of brick or stone veneer. Use ventilation plugs from a hardware store in those instead.

Can I keep boxelder bugs out of a house with vinyl siding?

Partly. Minnesota Extension says older houses with vinyl siding may have too many gaps to keep boxelder bugs out completely. Newer houses often have house wrap under the siding that keeps most insects out, though bugs may still settle between the siding and the wrap. On these houses, the bugs usually bunch up around doors and entryways in fall.

How to Get Rid of Boxelder Bugs in the House

A vacuum is the best tool once they are inside. Minnesota Extension says the best option indoors is a vacuum or a broom and dust pan, and that trying to treat wall voids and other hiding spots is not practical. It does not recommend insecticides indoors, since the bugs only live a short time once they emerge.

UW Extension adds two practical tips. Use a hose attachment so you do not stain fabric, and empty the vacuum right away, because boxelder bugs can crawl back out.

Does soapy water kill boxelder bugs?

Yes, on contact. UW Extension describes a home remedy of a 3 to 4 percent mix of soap in water, by volume, sprayed directly on the bugs. Soap only kills the bugs it hits, so it does nothing to stop the next ones.

Should I cut down my boxelder tree?

Probably not. UW Extension notes that removing all the boxelder trees in an area prevents breeding, but Minnesota Extension advises against removing or spraying the trees in your own yard. Adult boxelder bugs can fly up to a couple of miles, so the neighborhood will still supply them, and Minnesota Extension judges the benefits of boxelder, maple and ash trees to outweigh occasional infestations.

How to Get Rid of Boxelder Bugs With an Outdoor Insecticide

An outdoor treatment can help if you get large numbers every fall. Minnesota Extension says the best time to spray is late summer and early fall, when the bugs first cluster on the outside of the building, and that insecticide should supplement sealing, not replace it.

Check the label for directions that allow use on the exterior of buildings. Active ingredients sold to homeowners that Minnesota Extension lists include bifenthrin, cyfluthrin, deltamethrin, lambda cyhalothrin and permethrin. UW Extension notes some insecticides do not work well in cool temperatures, but insecticidal soap or sprays with permethrin, cyfluthrin or esfenvalerate are effective. Always follow the label.

Is it worth spraying boxelder bugs in spring?

No. In spring, the boxelder bugs on your siding are leaving the places they spent the winter and moving away from the house. Minnesota Extension says spraying them then is unnecessary and has no effect on how many show up the following fall.

Are the orange beetles on my windows boxelder bugs too?

They are more likely multicolored Asian lady beetles, the other common fall invader. Look for a black M-shaped mark behind the head. Minnesota Extension says these beetles head for the sunny sides of buildings between late September and late October, and like boxelder bugs they do not reproduce indoors. They can bite hard enough to break skin, their yellowish fluid can stain light surfaces, and dead beetles can cause allergic reactions in some people. Minnesota Extension recommends using control measures only to keep them from getting indoors, so the same sealing work pays off twice.

How to Get Rid of Boxelder Bugs With Help From a Pest Control Company

Call a pro if you get heavy infestations every fall or cannot reach the gaps yourself. Minnesota Extension notes that a professional pest control service has the equipment and expertise to treat the house and may be the best option for the worst infestations. It works best if they treat in late summer or early fall, before the bugs get inside. Browse the pest control companies in Eau Claire in our directory.