Box elder bug - Definition

The Box elder bug or Maple bug (Leptocoris trivittatus or Boisea trivittatus; there is disagreement over the genus) is an insect found primarily on maple and ash trees. The adults are about 12.5 mm long with a dark brown or black coloration, relieved by red wing veins and markings on the abodomen. Nymphs and immature bugs are bright red.

These insects feed on the softer plant tissues, including leaves, flowers, and new twigs. Unless the population is exceptionally large, the damage to plants is minimal. During years when their population soars, they can damage useful shade trees.

The real problem occurs after summer, when they become houshold pests. The adult stage insects seek wintering hibernation locations and find their way into buildings through crevices. They remain inactive inside the walls while the weather is cool. When the heating systems revive them, they begin to enter inhabited parts of the buildings. They do not bite, sting, or damage anything, but their presence is an undesirable nuisance in the opinion of many.

In the spring, the bugs leave their winter hibernation locations to lay eggs on maple or ash trees (their preference is Manitoba maple or box elder, Acer negundo).