Carpenter bees are large and have a blue-black, green or purple metallic sheen. They often burrow into exposed dry wood of buildings. Infestations are often detected by finding large amounts of sawdust on the ground below the area being drilled. The galleries are made by the female and usually average 4 to 6 inches in length. She then furnishes the nest with "bee bread" (a mixture of pollen and regurgitated nectar) and lays an egg on top of it. The female then closes the cell with chewed wood pulp. There may be a number such sealed cells in a linear row in one gallery (see figure below).
Carpenter bees resemble bumblebees (see figure below), but they are not social insects, and most of the top part of their abdomen is without hairs. The males are at times quite annoying because they fly around the heads of human but are quite harmless because they lack a sting. The females possess a potent sting but they use it rarely. While the damage to wood from the drilling activity of a pair of carpenter bees is slight, the activities of numerous bees during a period of years can cause considerable damage.