The boxelder bug (Boisea trivittata) is a common North American insect, easily identified by its black body and distinctive reddish-orange markings, typically measuring about half an inch in length. They are primarily recognized as household nuisances due to their habit of congregating in large numbers, especially near homes as the weather cools. This tendency to swarm and occasionally invade human dwellings often leads to questions about their potential to transmit illness.
Are Boxelder Bugs Vectors for Disease?
The definitive answer to whether boxelder bugs carry and transmit disease to humans or pets is no. Scientific consensus holds that Boisea trivittata is not a vector for any known bacterial, viral, or parasitic human or animal pathogen. They present no primary health threat, making them a nuisance pest rather than a medical concern.
Boxelder bugs do not feed on blood, which is the common route for disease transmission in many insect vectors like mosquitoes or ticks. Their mouthparts are designed for piercing and sucking plant fluids, primarily from the seeds of boxelder, maple, and ash trees. They do not acquire or spread infectious agents that cause illness in people or domestic animals.
Actual Hazards and Nuisances
While boxelder bugs do not pose a health risk, their presence creates several distinct nuisance issues for homeowners. The most common complaint involves the reddish-orange stains left behind by their excrement. This fecal material, often deposited on surfaces like curtains, walls, and window ledges, can be difficult to clean and may result in permanent discoloration on light-colored fabrics.
Another nuisance is the possibility of minor skin irritation. Boxelder bugs possess piercing-sucking mouthparts and may probe human skin if they become trapped or startled, though they do not bite defensively. This rare action results in a temporary red spot and slight irritation, comparable to a mild mosquito bite. Furthermore, when crushed, the insects release a foul-smelling secretion as a defensive mechanism, which often discourages manual removal.
Prevention and Management
The most effective strategy for managing boxelder bug populations is exclusion, preventing them from entering the home for overwintering. As temperatures drop in late summer and early fall, the bugs aggregate on sun-warmed surfaces, seeking small cracks and crevices. Homeowners should inspect the structure’s exterior and seal any openings larger than one-eighth of an inch.
Sealing includes applying caulk around utility openings, such as pipes and cables, and ensuring that all window and door screens are intact and properly fitted. Installing weather stripping around doors and windows can also eliminate potential entry points.
Reducing harborage sites outside is also beneficial; this involves clearing away leaf litter, wood stacks, and debris near the foundation where the bugs can shelter. If bugs are found inside, manual removal with a vacuum cleaner is the preferred method to avoid crushing them and releasing the staining excrement and odor.