Box elder bugs are common pests over much of the United States. Adults are about 1/2 inch long. They are bright red or black with narrow reddish lines on the back. Box elder bugs feed principally by sucking juices from the box elder tree, but are sometimes found on other plants. They do very little damage to the trees they attack, but at certain times of the year they can become a nuisance. Box elder bugs develop by gradual metamorphosis, from egg, to nymph, then to adult.