In the late-spring and early summer, homeowners often notice large, black bees hovering around the outside of their homes. These are probably carpenter bees searching for mates and favorable sites to construct their nests. Male bees are quite aggressive, often hovering in front of people who are around the nests. The males are quite harmless, however, since they lack stingers. Female bees can inflict a painful sting but seldom will unless they are handled or molested.
How do I recognize Carpenter Bees?
Carpenter bees resemble bumble bees, but the upper surface of their abdomen is bare and shiny black; bumble bees have a hairy abdomen with at least some yellow markings.
Entrance holes are perfectly round. Despite their similar appearance, the nesting habits of the two types of bees are quite different. Bumble bees usually nest in the ground whereas carpenter bees tunnel into wood to lay their eggs. Bare, unpainted or weathered softwoods are preferred, especially redwood, cedar, cypress and pine. Painted or pressure-treated wood is much less susceptible to attack. Common nesting sites include eaves, window trim, facia boards, siding, wooden shakes, decks and outdoor furniture.
Carpenter bees prefer to attack wood which is bare, weathered and unpainted. Therefore, the best way to deter the bees is to paint all exposed wood surfaces, especially those which have a history of being attacked. Wood stains and preservatives are less reliable than painting, but will provide some degree of repellancy versus bare wood.