Carpenter bees look very similar to bumble bees, and are differentiated by looking at the abdomen. The carpenter bee's abdomen is black and shiny, whereas the bumble bee's abdomen has hairs on it and some yellow color.
Carpenter bees bore into wood to lay eggs and nest. The hole looks as if someone drilled a 1/4-inch round hole into the wood. They will overwinter in the tunnels in the wood and emerge in the spring for mating. At that time, the female will create a new nest or may even expand the older ones, creating even more damage. She will then lay six to eight eggs which will hatch about 40 days later, around late summer.