Approximately three quarters of North American bees are solitary, and the carpenter bee is one of them. Older classifications placed them in the Anthophoridae family, but they are now grouped in the Apidae family and Xylocopinae sub-family. The carpenter and little carpenter bee are often mistaken for other bees. Carpenter bees are large and resemble bumblebees, but their abdomen is smooth and shiny black, unlike the hairy abdomen of the bumblebee. The little carpenter bee can be mistaken for many of the smaller sweat bees.
Carpenter bees can live for up to three years, and can have up to two generations of offspring per year. The bees make their nests by tunnelling perfectly circular holes into wood, leaving a tell-tale pile of sawdust behind. Their preferred wood is usually bare, weathered, unpainted surfaces, or softwoods like redwood, cedar, cypress and pine. The bees are liable to burrow into any structure, such as decks, outdoor furniture, siding, wooden window trim, etcetera. Depending on the amount of damage done by carpenter bees, some structures may become unstable and in danger of collapsing. A precaution against attack is to paint the wood, which makes it less attractive to the bees.
The female bees dig tunnels in wood, and after mating, lay their eggs in a series of small cells. Sometimes the females will reuse old holes, or excavate to enlarge them. Pollen collected from flowers is placed in the cells for the larvae to feed on in their development. As adults, the bees forage flowers in search of nectar to survive.
Carpenter bees appear in the spring and early summer, and are noteworthy pollinators. Sometimes, if a flower is too small for the carpenter bee to enter or reach its nectar, the bee will resort to robbing the flower. The bees will cut into the bottom of the flower's corolla using their mouthparts, and take the nectar without ever coming in contact with the flower’s pollen, thus not pollinating the flower.