An interesting recent development has been an increase in calls concerning carpenter bees in southern Iowa. Inquiries about carpenter bees, a "southern" insect, were very rare until a year ago. Now, there have been 2 calls this week.
Carpenter bees resemble bumble bees but the upper surface of their abdomen is bare and shiny black; bumble bees have a hairy abdomen with at least some yellow markings.
Carpenter bees nest in exposed bare wood. A perfectly round hole the size of your finger is drilled into the surface a short distance. Then the tunnel turns and follows the grain of the wood for several inches. This tunnel is provisioned with pollen on which the larvae feed. New adults emerge in late summer.
Coarse sawdust the color of fresh-cut wood will often be present beneath the entry hole, and burrowing sounds may be heard from within the wood. Female carpenter bees may excavate new tunnels for egg laying, or enlarge and reuse old ones. The extent of damage to wood that has been used for nesting year after year may be considerable.
Bare, unpainted or weathered softwoods are preferred, especially redwood, cedar, cypress and pine. Painted or pressure-treated wood is much less susceptible to attack. Common nesting sites include eaves, window trim, fascia boards, siding, wooden shakes, decks and outdoor furniture.
For more information on carpenter bees I recommend the web page by Dr. Mike Potter, Extension Entomologist at the University of Kentucky.
We are interested in documenting the presence of carpenter bees in Iowa. So far, we have reports from the following counties (year reported): Appanoose (1981), Clayton (1982), Davis (1994), Decatur (2002), Fremont (2001), Henry (1997), Jefferson (2001), Lee (1988), Lucas (2001), Van Buren (2002), and Wayne (2000, 2001). If you see or hear of carpenter bees in your county, please drop us a line (email address: insects @iastate.edu).
This article originally appeared in the June 7, 2002 issue, p. 78.