Boxelder Bug

The boxelder bug, *Boisea trivittata*, is a true bug (Hemiptera: Rhopalidae), distinct from beetles by its piercing-sucking mouthparts and hemimetabolous metamorphosis. Adults measure 10-14 mm in length, characterized by a predominantly black dorsal surface adorned with three prominent red-orange longitudinal stripes on the pronotum and similarly colored veins along the outer margins of the forewings (hemelytra). Eggs hatch into bright red nymphs with black appendages, progressing through five instars over 28-30 days at optimal temperatures (25-30°C). A single female can lay 200-300 eggs, typically in clusters on host plant leaves or bark, with one to two generations per year depending on climate – often two in warmer, southern regions. Overwintering adults can live for several months, while a new generation of adults has a much shorter lifespan once reproduction occurs.

Boxelder bugs are primarily diurnal, actively feeding and basking during daylight hours, especially on sunny surfaces. Their social structure is largely aggregation-based, particularly evident during fall migration and overwintering, though they do not form eusocial colonies. Communication for aggregation primarily involves visual cues (e.g., sun-warmed surfaces) and possibly contact pheromones, though specific long-range aggregation pheromones are not well-documented. Their feeding ecology is specialized; nymphs and adults utilize piercing-sucking mouthparts to extract sap from the seeds, leaves, and tender twigs of host trees, primarily boxelder (Acer negundo), but also other maples (Acer spp.) and ash (Fraxinus spp.). While generally harmless to humans, large aggregations can be a nuisance, and when crushed, they emit a distinctive, pungent odor and orange-red stain, which can mark surfaces or fabrics.