Females can sting if they are disturbed. Their pollination ability is questionable-they can remove nectar without pollinating the plant by cutting small holes in flowers. Large male carpenter bees can be highly aggressive when defending their territory. There is one generation of carpenter bees produced per year. Adults emerge from old tunnels in April or May and mate.
Females then dig a tunnel, dropping sawdust on the ground under the hole.
The tunnel entrance is almost a perfect circle. Wood piles, unpainted fence posts, fascia boards, eaves and decks are the preferred places of attack, and soft woods are favored over hard woods. The tunnel is perpendicular to the wood surface for the first one to two inches, makes an abrupt right angle turn, and then runs parallel to the grain of the wood for four to six inches. She then seals off the chamber by making a thin wall from chewed wood pulp. The process is repeated five to seven more times in the same tunnel.