The common eastern carpenter bee, Xylocopa virginica, is the carpenter bee most often encountered in the eastern United States. It is often mistaken for a large bumblebee species, as they are similar in size and coloring. They can be important pollinators, especially of open-faced flowers, though they are also known to "rob" nectar by boring holes in the sides of flowers with deep corollas (thus not accomplishing pollination). They sometimes bore holes in wood dwellings and can become minor pests. They use chewed wood bits to form partitions between the cells in the nest. From Wikipedia