Boxelder bugs (Boisea trivittata) are a common insect recognized by their black bodies with distinct red-orange markings. They become conspicuous during the fall as temperatures drop, leading them to abandon their outdoor feeding grounds. They instinctively aggregate in large numbers near or inside structures, seeking protected overwintering sites before the onset of cold weather.
The Boxelder Bug’s Typical Diet
During the active spring, summer, and early fall months, boxelder bugs are primarily phytophagous, meaning they feed on plants. They are strongly associated with the Acer family of trees, particularly the female, seed-bearing boxelder tree (Acer negundo). Their diet consists mainly of sap, the developing seeds, and the leaves of boxelder trees, which they rely on to build up fat reserves. They will also occasionally feed on the seeds and leaves of other maples, such as silver maples, and ash trees if their preferred food source is less available.
Winter Survival Strategy: Diapause
Boxelder bugs enter a state of physiological dormancy called diapause during the winter. This survival strategy is triggered by decreasing daylight hours and cooling temperatures, which dramatically reduces their metabolic rate. They survive entirely by metabolizing the stored body fat accumulated during the previous autumn feeding frenzy.
Only adult boxelder bugs are equipped to survive the winter conditions, while nymphs typically perish with the first hard frost. To initiate diapause, they seek warm, protected locations, often choosing cracks, crevices, or wall voids within structures. These overwintering sites are frequently located on the south or west sides of buildings, which receive the most sun exposure. If internal heating warms their hidden space significantly, the bugs may temporarily emerge from diapause and wander indoors, but they are not searching for food.
Dealing with Indoor Boxelder Bugs
When boxelder bugs emerge inside a home during the winter, physical removal is the most effective control method. The simplest technique is to use a vacuum cleaner with a hose attachment to collect the insects without handling them. Immediately dispose of the vacuum bag or canister contents outside, as the bugs may otherwise crawl back out.
Avoid crushing the insects, as they can release a foul-smelling chemical and leave a reddish-orange stain on fabrics and carpets. Boxelder bugs pose no threat to the home’s structure or people while they are inside, as they remain in a non-feeding state. The best long-term solution involves sealing exterior entry points, such as utility openings and cracks around windows, during the late summer or early fall to prevent entry.