If you find coarse sawdust the color of fresh-cut wood beneath a hole the size of your finger you may have found active carpenter bees.

Carpenter bees look similar to bumble bees, but act differently according to entomologists with Iowa State University. While bumble bees are social living in colonies, carpenter bees are solitary and nest by drilling holes in wood. The holes can often be found in exposed wood like deck joists or shed rafters. Carpenter bees are bare and shiny black while bumble bees have a hairy abdomen with some yellow markings. New adult carpenter bees emerge in late summer. The bees prefer unpainted or weathered softwoods like redwood, cedar, and pine. Painted or pressure-treated wood is less susceptible to boring by the bees.