Carpenter Bees Spring Into Action

— Written By Michael Waldvogel
Female carpenter bee drilling hole in spindle

Female carpenter bee drilling hole in spindle (Image – M. Waldvogel, NC State University)

Warm weather brings people outdoors for their spring lawn and garden activities. It also signals the start of carpenter bee activity. What we see near the end of March and early April is mostly male bees which can be recognized by the white spot on the front of their head. You may unwillingly get a view of that white spot if you are sitting on wood bench or deck as the males buzz about anxiously awaiting the appearance of female carpenter bees who have been passing the winter in nearby old galleries. After mating, the female begins the task of drilling out a new gallery (see photo at right) which will house her offspring in individual cells within the gallery.

Entrance to carpenter bee gallery

Entrance to completed carpenter bee gallery (Image – M. Waldvogel, NC State University)

Most of the time, real damage to wood is minimal. However, over time, repeated drilling of new galleries can become significant. Additionally, there is always the chance of damage by woodpeckers as they dig out bee larvae from the galleries.

There are still no “silver bullets” for preventing carpenter bees from drilling other than using non-wood composite building materials. Favored targets for the bees are area such as fascia boards, trim along with the undersides of porch rails and the spindles (balusters). Some people use carpenter bee traps which will catch some bees but whether they “control” the bees is in the eye of the user.

Surface sprays typically have limited surface residual to be truly effective (or durable). We still recommend applying an insecticidal dust to the holes and then caulking them about 24 hours later. Remember that when you’re spraying/dusting a carpenter bee gallery, keep a safe distance between your face and any possible backsplash. Be equally careful when spraying up over your head. The laws of gravity apply equally to pesticides and the higher you spray, the more likely that some chemical may drift as well. Consult the NC Ag. Chemicals Manual page (170) for chemicals that can be used for this job.

For more information about carpenter bees:

Extension Factsheet attach_file

Carpenter Bees

This Entomology Insect Note discusses the biology and control of carpenter bees, which bore tunnels in wood with their strong jaws.