Carpenter bees are large insects. They look like bumblebees except they are solid black and have smooth, shiny abdomens. Bumblebees have yellow markings and they look very fuzzy. An adult carpenter bee can be almost 1″ long.
Carpenter bees get their name from the way they damage wood. The female carpenter bees make tunnels into wood for nesting and laying eggs. They attack decks, siding, eaves, railings, and even wooden lawn furniture.
The female carpenter bee starts by making a hole in the wood. After a short distance, she turns and begins digging a tunnel that follows the grain. The tunnel can extend for several inches. If the bee is re-using a tunnel from the previous year, she will usually extend it. After a few years, carpenter bee tunnels can extend a long way into the wood.
The female bee deposits a small pile of pollen and nectar at the end of the tunnel. She places an egg beside the pile and seals the chamber. She repeats the process over and over until the tunnel is filled with egg chambers. When the egg chambers are finished, the female carpenter bee leaves.
When the eggs hatch, the larvae eat the pollen and nectar while they develop. When they are adults, they crawl out of the tunnel.
If carpenter bees have been active around the home, each tunnel should be treated with insecticide. The objective is to apply something that will eliminate the female bees immediately. The insecticide should also remain effective so it can eliminate the bees that hatch in a few months.
Dust insecticide is usually the most effective and practical treatment for carpenter bees. The dust will not soak into the wood, so it will remain effective. A wettable powder insecticide can also be effective. It is applied as a liquid, and then when it dries, it leaves a powder on the surface.
Insecticide injection requires special equipment. Safety is a concern to prevent insecticide splashing into the face of the person making the treatment. Many people prefer to contact a pest control professional to do these treatments.
After the insecticide has been applied, do not seal the holes for a few days. After the female carpenter bees have been exposed to the insecticide, the holes can be plugged with putty or wooden dowels. .
Homeowners can protect exterior wood by applying paint or a similar durable sealer. Scientists believe that carpenter bees are less likely to attack wood that has been painted or sealed.