Boxelder bugs (Boisea trivittatus) are a common nuisance insect, recognizable by their black bodies and distinctive reddish-orange markings. These insects do not bite, sting, or cause structural damage to homes, but they become problematic when they gather in large, conspicuous numbers. Their primary motivation for entering a home is to find warm, sheltered locations to survive the colder months, a behavior known as overwintering. Homeowners experience an influx during the fall as the bugs seek refuge and again in the spring as they attempt to exit. The goal of management is to make the home and surrounding area undesirable, employing both immediate and long-term strategies to repel and exclude these pests.
Active Repellent Sprays
Boxelder bugs actively avoid substances that compromise their outer structure or mask their aggregation pheromones. A simple, non-toxic solution of dish soap and water is one of the most effective immediate control methods. Mix one to two tablespoons of liquid dish soap into a quart of water in a spray bottle to create a contact killer. The soap acts as a surfactant, dissolving the insect’s protective waxy exoskeleton, which causes rapid dehydration and death. This solution should be applied directly to the clusters of bugs often found congregating on the sunny exterior walls of a home.
For a more subtle deterrent, essential oils with strong scents can be utilized near entryways. Oils like peppermint, clove, eucalyptus, or lavender are known to be repellent to these insects. A mixture of about ten drops of oil per cup of water can be lightly spritzed around window frames and door sills.
Physical removal is another immediate action that the insects cannot tolerate, especially for those that find their way indoors. Using a vacuum cleaner to suck up visible bugs is the cleanest method of disposal, preventing the release of the foul odor and staining liquid that occurs when they are crushed. After vacuuming, the contents should be sealed in a plastic bag and immediately disposed of outside to ensure the bugs do not escape.
Removing Environmental Attractants
A long-term strategy for boxelder bug control involves making the surrounding environment unattractive by eliminating their preferred food and shelter sources. The insects are named for their primary host, the female boxelder tree, as they feed on its seeds, but they also use maple and ash trees. Pruning or removing female seed-bearing trees closest to the structure can significantly reduce the local population by removing the main food source. Additionally, cleaning up fallen seeds, particularly in the spring, prevents the young nymphs from developing near the home.
Boxelder bugs are strongly attracted to warm, sunny surfaces, often congregating on south- and west-facing walls to bask in the heat and regulate their body temperature. They release aggregation pheromones on these surfaces, which attracts more of their kind. Washing down these sun-exposed areas with a soapy water solution helps to eliminate these chemical signals, making the location less appealing for gathering.
Eliminating debris and clutter near the foundation is also important, as boxelder bugs seek out protected overwintering spots. Removing leaf piles, wood stacks, and other garden debris near the house reduces potential hiding places.
Sealing Entry Points
The most effective method for prevention is creating a physical barrier that the insects cannot bypass, denying them access to warm, sheltered interior spaces. Boxelder bugs are flat-bodied and can squeeze through very small openings, seeking out cracks as tiny as 1/8 of an inch. A thorough inspection of the home’s exterior should be conducted before the bugs begin seeking shelter in the fall.
Use silicone or latex caulk to seal small gaps around window frames, door frames, and where utility lines or cables enter the home. Replace any worn or damaged weatherstripping on doors and windows to eliminate easy access beneath and around the seams. Ensure that all window and roof vents are fitted with tight, intact screens, preferably fine mesh, to block the bugs without impeding airflow.
Physical barriers should also be installed around the foundation, paying close attention to gaps in the siding, soffit vents, and any cracks in the concrete. Sealing these entry points prevents the bugs from accessing wall voids and attics where they can hide and emerge unexpectedly inside the living space.