The boxelder bug, Boisea trivittata, is a true bug easily identified by its half-inch long black body accented with striking reddish-orange markings along its wing edges and back. These insects often cluster in large groups during the autumn, drawn to warm, sunlit surfaces as they seek shelter to overwinter. Their primary food source is the seeds of the female boxelder tree, though they also feed on maple and ash trees. While they do not cause structural damage, their sheer numbers and the potential for staining surfaces with excrement make them a significant nuisance pest. This article will focus exclusively on natural, non-chemical methods for managing boxelder bug populations outdoors.
Active Removal Methods
Immediate and direct action is necessary when large clusters of boxelder bugs gather on exterior walls or trees. A simple and effective solution is a homemade insecticidal spray utilizing dish soap and water. Mix one to two tablespoons of liquid dish soap—not dishwasher detergent—into a spray bottle or garden sprayer filled with water. The soap mixture works by dissolving the insect’s protective waxy outer coating, known as the cuticle, leading to rapid dehydration and death.
This spray must make direct contact with the bugs to be effective, so thoroughly saturate the clustered insects until they disperse. For high-volume removal, particularly on vertical surfaces like siding, a wet/dry shop vacuum offers an efficient method for physical removal. Once the insects are collected, dispose of the vacuum contents promptly, such as by sealing a disposable bag or emptying the canister into a bucket of hot, soapy water. This prevents the captured bugs from escaping the vacuum and minimizes the release of the unpleasant odor they emit when crushed.
A strong jet of water from a garden hose can also be used to dislodge aggregated bugs from surfaces like tree trunks, fences, or patios. While high-pressure water does not kill the insects, it physically removes them from their basking or clustering spots. Repeated spraying may be necessary as the bugs will quickly return to warm, sun-exposed areas on the south or west side of a structure. After any removal method, wiping down the area with soapy water can help eliminate the scent trails that attract other boxelder bugs to the same location.
Preventing Entry to Structures
The most effective strategy for managing boxelder bugs involves physically blocking their access to the interior of a home, especially during the fall when they seek overwintering sites. Begin by inspecting the building’s exterior for any gaps or openings that measure as small as an eighth of an inch, which is enough space for these insects to enter. Cracks around window and door frames, utility lines, and the foundation should be sealed using durable materials such as silicone or silicone-latex caulk.
Weatherstripping should be installed or replaced on all exterior doors and windows to eliminate the narrow gaps that form around their perimeters. Even small openings around exterior electrical boxes and cable entry points require careful attention. Any exhaust vents, including those for the dryer or attic, and chimney openings must be secured with fine mesh screening to prevent insect entry.
Window and door screens should be checked for tears or holes and repaired or replaced to ensure they fit tightly within the frame. Boxelder bugs are attracted to the warmth radiating from the home’s structure, often congregating on sun-drenched south- and west-facing walls. Establishing a thorough, continuous barrier around the entire perimeter denies the insects the shelter they seek for hibernation.
Long-Term Landscape Deterrents
Controlling boxelder bug populations over the long term requires modifying the outdoor environment to reduce their food sources and preferred shelter. Boxelder bugs rely heavily on the seeds produced by female boxelder trees (Acer negundo), which are their primary host, but they also feed on certain maple and ash tree seeds. If feasible, removing female boxelder trees that are close to the home can significantly reduce the local population, as the bugs must be near host trees to complete their life cycle.
Where tree removal is not an option, diligently raking and removing all fallen seeds and fruit around the foundation and yard is necessary to eliminate a major food source. Boxelder bugs seek out protected, dry locations for overwintering. Maintaining a clean, debris-free perimeter extending several feet from the home’s foundation removes these preferred hibernation spots:
- Leaf litter
- Woodpiles
- Rocks
- General yard debris
The insects are also attracted to areas with moisture, so ensuring proper yard drainage and eliminating any sources of standing water is helpful. Trimming back overgrown vegetation and tree branches that touch the house walls reduces the pathways the bugs use to climb onto the structure.