Box elder bugs are a common sight across North America, becoming a nuisance when they aggregate near homes, particularly in the fall. These small, black, and red insects are not harmful, but they congregate in large clusters on sunny exterior walls, especially those facing south or west. This congregation precedes their search for sheltered, warm places to overwinter, often leading them to invade structures. Successfully repelling these insects requires a layered strategy combining immediate deterrence, structural exclusion, and the elimination of outdoor attractants.
DIY and Natural Repellent Sprays
A simple insecticidal soap solution is an effective contact spray for immediate reduction of visible clusters. This mixture is typically created by combining mild liquid dish soap with water, using a ratio of approximately one to two tablespoons of soap per gallon. The soap acts by breaking down the insect’s protective outer layer, leading to dehydration and eventual elimination. Apply this solution directly to the bugs or areas where they are congregating on exterior surfaces.
White vinegar, diluted with an equal part of water, provides a different type of repellent action. The strong, pungent scent of the acetic acid is unpleasant to the insects, serving as a deterrent. The mixture may also disrupt the chemical scent trails that box elder bugs use to communicate and gather. This spray is best used around potential entry points, like door frames and window sills.
Aromatic essential oils, such as peppermint, clove, or eucalyptus, can be utilized as a short-term repellent. These oils are heavily diluted, often using 10 to 50 drops of oil per cup of water, and then sprayed onto surfaces. Although the effects are temporary and must be reapplied, the strong scent discourages the insects from congregating on sunny walls where they seek warmth.
Sealing Entry Points
Preventing box elder bugs from entering the home is a structural form of repulsion that addresses their need for overwintering shelter. These insects are adept at finding minute openings and can squeeze through cracks as small as one-eighth of an inch. Inspecting the entire perimeter in the late summer or early fall is the best time to perform this exclusion work.
Cracks in the foundation, gaps in siding, and utility penetrations around pipes and vents must be sealed using a high-quality, durable caulk. Special attention should be paid to the seams where different materials meet, such as masonry and wood trim. This sealing process blocks access to wall voids and attic spaces where the bugs seek refuge.
The integrity of all windows and doors must be addressed to maintain a complete barrier. Ensure that all screens are free of tears and fit tightly within their frames. Installing or repairing door sweeps on all exterior doors eliminates common access points found at the threshold.
Eliminating Outdoor Attractants
Long-term reduction in box elder bug populations requires removing the elements that attract them to the property. The insects primarily feed on the seeds and sap of their host trees, specifically the seed-bearing female box elder trees (Acer negundo). They may also feed on other species, including certain varieties of maple and ash.
Removing female box elder trees from the immediate vicinity of the home is the most effective way to eliminate the primary food source and breeding ground. If removal is not feasible, regularly raking and disposing of fallen seed pods during the spring removes a necessary food source for developing nymphs. Eliminating nearby food reduces local populations, even though adult bugs can fly for several blocks.
Box elder bugs also seek sheltered environments in the landscape to hide and overwinter. Keeping the yard free of debris, such as leaf litter, grass clippings, and wood piles, removes these favorable hiding spots. Trimming back overgrown shrubs and plants that touch the foundation also reduces the number of protected locations where the insects can begin their migration toward the home.