Carpenter Bees are a destructive bee that creates tunnels in desirable wood, on and near homes. They bore a hole nearly a 1/2 inch in diameter, see middle image, then a tunnel 8 to 10 inches long, down the length of the board. This can weaken the structural integrity of the wood, causing the homeowner to have to repair or replace damaged wood. There are a number of species of Carpenter Bees found throughout the United States. The most common one in many areas is the large bee that looks like a bumble bee.
Note the abdomen on the CB is hairless and on the BB hairy. See the two closer images, the dark bee with the shiny body and wings is the other common CB. The dark one is the female and the golden one is the male. Males have no stinger, only the females can sting.

The young adults over-winter in the tunnels, then they mate and clean out and enlarge old tunnels or create new ones. then they create a mixture of pollen and regurgitated nectar that is placed at the end of the tunnel and one egg is placed on this “food” and the chamber is sealed off, see bottom image with larvae in chambers. In the fall the young adults emerge and feed on nectar, then return to the tunnels to over-winter.

CB prefer to borer into bare, weathered and unpainted wood. The best way to deter CB is to paint exposed wood surfaces. It is recommended to use paint, not stain or water-proofers. The most effective control for CB is to use a chemical dust and a puffer and apply it into the holes.

Hi-Yield Multi-Use Dust is a Deltamethrin dust on a talc-like carrier, it is nearly water-proof so it can not be washed off. This also makes it the longest lasting dust available. Apply in the very early morning or late evening, in spring or fall when they are coming and going into the holes. The CB doesn’t need to be in the hole when you apply, if they enter the hole after application and get into the product they will ingest it when they clean themselves and die later.

If you are afraid to get near the holes, an application of FL Wasp & Hornet Killer may be used, it will spray up to 20 feet. No climbing necessary. If the area is very large, Bifenthrin has been shown to be very effective on CB. Mix Hi-Yield Bug Blaster at the labeled rate and spray, repeat again in 2 weeks. Repair the holes with putty or caulk.