What Are Boxelder Bugs?

Adult Boxelder Bugs

Flattened, oval, black body with red markings, red eyes, six legs, and long antennae. Two black wings with red ridges that create an "X" or "W" pattern when laid back.

Boxelder Nymphs

Smaller versions of adults with bright red bodies that do not darken or develop wings until final molts. Typically clustered together creating bright red patches on tree surfaces.

Warm Weather Behavior

Boxelder bugs spend much of the year sunning themselves on tree surfaces to stay warm. Their nymphs primarily feed on boxelder seed pods. They can be found on boxelder, maple, and ash trees.

Cold Weather Migration

As temperatures drop in fall, boxelder bugs migrate to warm places to overwinter. They may take refuge in tree cavities, but often find cracks and crevices leading inside homes.

Aggregation Pheromone

If boxelder bugs find a safe place inside your home, they will release a pheromone that attracts other boxelder bugs. During winter, they remain mostly dormant in hibernation.

Spring

Adults awaken from hibernation and return outside to feed on boxelder trees

Summer

Eggs laid on female seed-bearing boxelder trees; by mid-July, large clusters visible

Fall

Mature bugs leave trees seeking warm places; nymphs that do not mature will not survive winter

Winter

Boxelder bugs lay dormant in their hibernation spots until spring

Nymph Diet

Nymphs rely on boxelder seed pods as their primary food source, which is why reproducing boxelder bugs are found on or near female boxelder trees.

Adult Diet

Adults feed on boxelder, maple, ash, plum, and apple trees. They mostly feed on leaves but can also feed on fruit, causing bruising, scarring, and deformation.

Outdoor Damages

They drain fluids from leaves and fruits, causing browning, bruising, and scarring. Damage is largely aesthetic and does not significantly impact plant health.

Indoor Damages

Their fecal matter stains fabrics a reddish color. They also leave bright red stains if smashed or crushed. They do not cause structural damage or contaminate food.

Outdoor Signs

Large clusters of boxelder bugs on tree surfaces from late spring to late fall.

Indoor Signs

Large clusters indoors or reddish fecal stains on fabrics and surfaces where boxelder bugs have been.