Boxelder bugs are common insects. These bugs are about half an inch long, featuring black bodies with prominent orange or red markings. Their wings often overlap to form an “X” shape on their backs, and they possess six legs and two antennae. While they do not cause harm to humans or significant damage to property, boxelder bugs can become a nuisance when they gather in large numbers around homes.
Preferred Host Trees
Boxelder bugs are drawn to specific trees. These trees, particularly female boxelder trees (Acer negundo), provide their primary food source and breeding grounds through their seeds and sap. Bugs use their piercing-sucking mouthparts to extract fluids from the seeds, leaves, and young branches. This feeding behavior, while sometimes causing discoloration or minor damage to foliage, does not severely harm the trees.
Beyond boxelder trees, these insects also feed on other trees within the maple family and ash trees, especially when their preferred food sources are less available. They may feed on the fruits of apple, plum, and cherry trees, extracting juices rather than consuming the flesh. The presence of these host trees on or near a property increases the likelihood of attracting boxelder bugs.
Overwintering and Gathering Sites
As temperatures drop in the fall, boxelder bugs seek warm, sheltered locations for overwintering. They congregate in large numbers on sunny, south-facing walls of homes and other structures. Taller or standalone buildings in open areas are also attractive. They are cold-blooded and rely on the sun’s warmth to remain active.
Once on structures, these bugs exploit openings to enter buildings. Common entry points include gaps around windows and doors, utility pipes, and tears in window screens. While inside, they do not reproduce or feed, but their numbers can make them a nuisance, often found around windows as they seek out light and warmth during mild winter days. They can hide in undisturbed areas like attics, basements, and wall voids until spring when they attempt to move back outdoors.
Minimizing Their Attraction
To reduce the appeal of a property to boxelder bugs, focus on sealing potential entry points. Inspect and seal any cracks or gaps around windows, doors, and foundations using caulk or weatherstripping. Repairing torn window screens and ensuring proper sealing around vents and utility pipes also helps prevent indoor invasions. These measures create physical barriers that deter bugs from entering.
Additionally, managing the landscape can reduce their presence. Removing fallen seeds from female boxelder trees, especially in the fall, eliminates a primary food source and breeding ground. While removing mature boxelder trees can reduce populations, it is not always practical or desirable. Trimming branches away from the house and maintaining general yard cleanliness by removing debris can also make the property less inviting to these insects.