It’s that time of year to hear the buzz of those big black and yellow bees flying around wooden structures, looking for a place to drill their nesting holes.
These bees look a lot like bumblebees, but they are very different. A few years ago, a new shed was built on a nearby farm and was immediately painted a nice grayish color to blend in with the other weathered wood buildings nearby. The carpenter bees were delighted and started drilling holes in the wooden beams under the side wings of the shed.
Soon the undersides of the beams were filled with ½-inch diameter holes, the tell-tale sign of the carpenter bee’s activity. This happened because that particular wood surface had not been painted. So, the best defense against carpenter bees is to paint the wood (stain is not as effective).
By their behavior, I knew that they were carpenter bees, not bumblebees, which nest in the ground.
You can also tell these two important pollinators apart by their appearance. They are both fuzzy with yellow and black stripes, but the bumblebee has a fuzzy abdomen while the carpenter bee’s is smooth and black. So look for the “shiny hiney” and you will know for sure which one you have!
Once the holes are drilled, the female carpenter bee lays eggs inside the gallery and fills it with “bee bread,” a mixture of pollen and nectar to feed the developing larvae. The series of larval galleries damages the structural integrity of the wood and weakens the building.
The holes can be treated with insecticide and then plugged, following directions in our Carpenter Bee fact sheet at the Clemson Extension Home and Garden Information Center: https://hgic.clemson.edu/factsheet/carpenter-bees.
Plugging the holes without treating only makes the problem worse, as the bee will drill further into the wood to get out.
Another option is to construct carpenter bee traps from simple materials or purchase them online. Most consist of a small wooden box with ½-inch diameter holes drilled in each side and a plastic water bottle suspended below. Hang the traps from overhangs at the corners of the house, porch, deck, shed, or barn. Carpenter bees searching for nesting sites enter the holes in the wooden box, fall into the plastic bottle, and are not able to find their way out, eventually dying. Dead bees are disposed of by unscrewing and rinsing out the bottle. More information on carpenter bee traps can be found in the University of Kentucky’s Entomology factsheet at https://entomology.ca.uky.edu/ef611.
Please remember that both bumblebees and carpenter bees are beneficial, as they pollinate garden plants and crops. Carpenter bees are excellent pollinators of eggplant, tomato and other vegetables and many types of flowers. Without pollination, these crops would not be able to produce fruits or seeds.
If the infestation of carpenter bees is in an old building or wooden structure that is not being used, then consider leaving them alone to do their job protecting our food supply. Another thing to remember while they are buzzing around is that the carpenter bee is not very aggressive. The male does not even have a stinger. The female does, but rarely stings.
I hope you enjoy watching both carpenter bees and bumblebees pollinate your garden flowers as much as I do!
Trish DeHond is the home horticulture agent and Master Gardener coordinator for Clemson Extension in Darlington and Florence counties. She can be reached by email at email@example.com.Clemson University Cooperative Extension Service offers its programs to people of all ages, regardless of race, color, gender, religion, national origin, disability, political beliefs, sexual orientation, gender identity, marital or family status and is an equal opportunity employer.