INTRODUCTION. Carpenter bees get their common name from their habit of boring into wood to make galleries for the rearing of young. Common sites they choose to "drill" include eaves, siding, window sills, under decks and railings. They prefer untreated wood or well-weathered wood. Look for sawdust under the holes. They bore perfectly round holes in wood, making long interior tunnels, with the grain of the wood. RECOGNITION. Look for large bumble bees usually hovering near wood. Adult bees are about 1" long and robust in form. The Carpenter bee is black and has markings of yellow hair. The Carpenter bee nests in wood, where the Bumble bees build their nest on the ground. BIOLOGY. Carpenter bees are not social insects and do not live in colonies. The adults live through winter, typically in abandoned nest tunnels. In the spring, the survivors emerge and feed on nectar. Then mating begins and extends into nest-construction time. The mated female may reuse an old gallery, construct a new one by expanding an old gallery or bore an entirely new one. The female typically bores a circular hole (same diameter as her body) straight into the wood across the wood grain for a distance equal to her body length. Then the gallery takes a right-angle turn, usually with the grain of the wood and parallel to the outer longitudinal surfaces. New galleries average 4-6" (10-15 cm) long but galleries developed/used by several bees may extend up to 10 feet (3 m). The female provisions each gallery cell starting at the closed end of the gallery with a mass of pollen and regurgitated nectar upon which she lays a single egg. This portion of the gallery is then sealed off with a chewed wood-pulp plug, making a chamber or cell. This process is repeated until a linear series of 5-6 cells is completed, about 1 cell per day. Male carpenter bees tend to be territorial and often become aggressive when humans approach, sometimes hovering a short distance in front of the face or buzzing one's head. Since males have no stinger, these actions are merely show. However, the female does have a potent sting, but is rarely used. CONTROL. Carpenter bee control consists of treating each individual gallery with an appropriately labeled pesticide. Dusts, wettable powders, micro-encapsulated sprays, and aerosol residual formulations work best. Newly matured bees should contact a lethal dose before they can emerge. Carpenter bees rarely attack painted wood. They can be discouraged from using wood by painting all sides of it.