Boxelder Bugs

The Boxelder Bug is a major pest of boxelder trees.  Boxelder bugs are primarily a nuisance pest because they enter structures to overwinter.

Adults are about 1/2" long, elongated oval body with a somewhat flattened head.  They are black with reddish lines.  The antenna is 4-segmented and about half body length.  The nymphs are similar to adults but lack wings although wing pads may be present and bright red in color.

The overwintering adults emerge from hibernation when the boxelder buds open and fly back to their host trees, usually in late April to early May.  The primary host plant is the boxelder tree, but they also occur on seed bearing silver maple trees.  They do not feed on the male trees.  In Autumn the boxelder will congregate on the south side of rocks, trees, and buildings where the sun hits.  After masses congregate, they may fly to nearby buildings to hibernate for the winter.

Inside, boxelder bugs are primarily a nuisance pest.  However their red fecal matter may cause a red stain, resulting in discoloration on curtains, drapes, clothing and other nesting places.  When crushed they produce a strong, disagreeable odor.  They occasionally "bite" people causing a skin irritation and producing a red spot similar to a small ulcer.

(Insect Information excerpted from the NPCA Field Guide to Structural Pests)