IDENTIFICATION:
Carpenter Bees resemble Bumble Bees. They are large, 3/4 to 1 inch long, heavy-bodied, blue-black to black-colored with a green or purplish metallic sheen. The thorax is covered with bright yellow, orange, or white hairs and the abdomen, especially on the top side, is black, shiny and bare without hairs. It is the males, with white markings on their head, that fly around aggressively, but they are harmless since they lack a stinger. Females have black heads, are docile and rarely sting. They have a dense brush of hairs on the hind legs, whereas Bumble Bees have large pollen baskets and numerous, yellow hairs on the abdomen. Larvae are sac-like, white and legless with brown, globular heads that bear small mouthparts. The pupil stage is passed in a silent cocoon.

LIFE CYCLES AND HABITS:
Both male and female Carpenter Bees live through winter as adults within their old nest tunnels. Adults emerge in the spring (April and early May) and mate. Females provision the tunnels or galleries with bee bread (mixture of pollen and regurgitated nectar), lay an egg on top of the mass and close the cell with chewed wood pulp. She excavates the gallery with her mandibles (mouthparts) at the rate of one inch in six days. The gallery has a clean-cut round entrance hole with sharp edges 3/8 to 1/2 inch wide (dime-sized) on the lateral wood surface. The gallery continues inward for one to two inches, and then turns sharply at a 90 degree right angle running in the same direction as the wood grain for four to six inches or up to 10 feet long, if used by many bees. Damage from a pair of bees is slight, but if used by many bees over several years, damage can be extensive.

PREVENTION:
Keep all exposed wood surfaces well painted (oil base or polyurethane) to reduce attacks. Wood stains will not prevent damage. Aluminum, asbestos, asphalt, vinyl siding, and similar non-wood materials will not be damaged. If practical, remove and replace damaged wood with chemical pressure-treated wood to discourage nest construction.