Have you seen or been bothered by large “bumble bees” flying around your house or getting rather up close and personal lately? The correct identity of these bees is the carpenter bee, the largest bee native to the U.S. It looks very much like a bumble bee but the carpenter bee has a bare abdomen rather than a yellow and black fuzzy one. These bare abdomens can be a shiny black to almost iridescent green. The bees, which overwinter as adults, have recently emerged and are looking for mates. The good news is that the male bees, which are much more aggressive than the females and usually the ones that are bothersome, are harmless and cannot sting. The females can sting but generally do not unless they are handled, not sure who would want to do that, or unduly aggravated.
After the bees mate the females will bore tunnels with their strong jaws, mandibles, into dead wood and lay their eggs. Carpenter bees prefer to bore into wood that is unpainted and weathered. The holes are about ½” in diameter. Historically and characteristically this dead wood has been dead tree limbs. However homeowners have provided a regular smorgasbord of easier to access opportunities for the tunneling. The bees’ preference is for softwoods that include pine, cedar or redwood. Look for tunneling damage in eaves, window trim, decks, and even outdoor furniture.
The best way to deter bees from tunneling is to keep all exposed wood surfaces painted. Stains and varnishes, which repel to some degree, are not as effective as paint. Insecticides placed in the tunnels will control the bees, however as native bees they are important and effective “generalist” pollinators. Prevention of wood boring by the carpenter bees around the home, by painting is preferable to eliminating them.