PEST LIBRARY · BOXELDER BUGS
Black-and-red bugs covering a sunny wall or collecting at your windows? Start with identification, then focus on the openings that let them inside. Supernova helps homeowners understand the problem and choose a practical treatment plan, without a long-term contract.
Adult boxelder bugs are about half an inch long, with a dark body, fine red markings, and wings that rest flat along the back. Look for three red lines just behind the head. Young bugs, called nymphs, are smaller and much redder, developing dark markings as they grow.
Color alone is not enough: several other insects also have red-and-black markings. A clear close-up photo is a useful starting point for identification.
Typical clues: groups resting on exterior walls, bugs gathering around window trim, and scattered individuals appearing indoors. They do not eat the wood framing of your home or reproduce indoors. Their main problems are nuisance activity, odor when crushed, and possible staining.
Identification reference: UC IPM: Boxelder Bug.
Boxelder bugs feed especially on female, seed-bearing boxelder trees, which are a type of maple. They also feed on other maples and ash. The source may be beyond your property: University of Minnesota Extension reports that adults may travel as far as two miles.
Do you have to remove the tree? No. Removing a problem host tree may reduce a local source, but it does not guarantee elimination because adults can arrive from elsewhere. Keeping a valued tree and managing activity around the home is a reasonable approach. UC IPM explains both the role of host trees and the limits of removing them.
In fall, adults seek protected places to spend the winter. Sunny walls offer warmth; gaps around trim, doors, and siding can lead to shelter. South- and west-facing surfaces are common gathering places.
Use the activity at your property to guide timing. A calendar date alone cannot tell us whether your home needs treatment.
Seasonal reference: Colorado State University Extension: Boxelder Bugs.
Indoor spraying is generally not the answer to bugs emerging from hidden spaces. Removing the visible bugs and improving exclusion is more useful. Cutting down a tree is not a guaranteed solution either, because adults can arrive from other properties.
Prevention reference: University of Minnesota Extension: Boxelder bugs.
For identification photos and a broader home sealing checklist, read our fall invader prevention guide.
Good control, with realistic expectations. Many of our customers choose Supernova primarily because of boxelder bugs. In our field experience, treatment provides strong control around the home, even when nearby trees continue supporting the population. Our goal is to reduce the nuisance and help keep bugs outside; we do not promise to eliminate every boxelder bug in the surrounding area.
For recurring exterior gatherings, Supernova combines targeted exterior treatment with recommendations for reducing entry points. The focus is the part of your home where bugs are collecting and gaining access, with treatment placement governed by the product label and the conditions at the property.
What to tell us: where you see the largest groups, whether they are getting indoors, and whether the same problem returns each fall. Photos and the timing of previous activity help make that conversation more specific.
What to expect: treatment can reduce activity, but a single visit does not make a building permanently insect-proof. Bugs already sheltered inside may continue appearing, and new adults can arrive from nearby areas. Entry-point repairs remain part of the longer-term solution.
If this is one seasonal problem, explore one-time service. For recurring pest concerns, see Supernova Shield. We can discuss which option fits the activity at your home.
Before a visit, read our pest control preparation and aftercare guide and follow the instructions provided for your treatment.
Supernova serves homeowners in Coeur d’Alene, Post Falls, Rathdrum, and Hayden; Moscow and Pullman; and Lewiston, Clarkston, and Asotin.
Find local service information for North Idaho, the Palouse, and the LC Valley. Tell us your town and what you are seeing so we can discuss the next step for your property.
They are primarily a nuisance rather than a wood-destroying pest. Rare bites have been reported, so avoid handling them. They can leave stains and release an unpleasant odor when crushed.
Adults sheltered in the building can become active as temperatures rise. Not all emerge together. Vacuuming the ones you see provides relief, but does not remove every hidden bug.
No. A few bugs outdoors may only need monitoring and entry-point repairs. Repeated large gatherings or indoor entry are reasons to discuss additional help. The response should fit the problem.
Contact us when groups begin collecting on the building, especially if you have had indoor activity before. Include your town, where the bugs are gathering, and whether you have already tried any treatments.
Tell us about pets and their outdoor spaces before the visit. Keep pets away from treatment areas for the period specified in your instructions. Move bowls, toys, and bedding as directed. Botanical products also require precautions. See NPIC’s guidance on pets and pesticides.
Request a free inspection and tell us where the bugs are gathering. We will help you decide on a practical next step.