Carpenter Bees are amazing insects that can cause some serious damage to wood on a structures. Carpenter Bees resemble Bumble Bees but they have very different nesting behaviors. They bore very long tunnels through out the wood and divide these tunnels into cells where individual larva will develop. Carpenter Bees are non social insects, although many females may infest the same structure at different locations. The galleries that the Carpenter Bees carve out are very complex.
Carpenter Bees complete one generation per year. The eggs a laid in the spring Larva and pupa develop in the closed cells during the Summer. Adult Carpenter Bees emerge in late Summer and return to the same tunnels to hibernate over the winter. In the Spring thew adults mate and the females lay eggs, completing the cycle. Because of the protection in the chambers it is highly recommended that a specialized Pest Control program is set up. A one time application will have limited effectiveness, especially because of this.
This is what Carpenter Bees damage and nesting activity looks like. It could get much worse especially if Woodpeckers start attacking it. It is very difficult to control Carpenter Bees. The holes need to be injected with specialized products.