Completely, non-professional opinion on carpenter bee control, and make sure they are carpenter bees and not bumble bees:
If you decide to go the insecticide route, you need to take a rather systematic approach to controlling carpenter bees- tracking down each of the active galleries and dealing with them.
First off, read the label and apply at label rates (more is not better).
Identify active galleries where females have nests, these are usually holes that are marked with waste (see picture), waste could accumulate on the ground below the hole, or you observe carpenter bees coming and going from the them. Inactive/abandoned galleries are used by the bees for overwintering.
If you can, try to do your control efforts at night, as the females will more than likely be home and not out foraging.
If you are using a liquid formulation, keep in mind that it will probably quickly soak into untreated wood, minimizing any residual activity. Residual activity is a good thing, as most insecticides are contact poison and you want the bees to encounter the chemical. With a liquid, you may be able to impregnate a cotton ball with the insecticide and insert it into the gallery. Alternatively, applying an insecticidal powder or wettable dust is a better way to maximize the contact. I am not sure what products are currently licensed and available to the public in your state, so I am not sure if powder or dust formulations are available. After application, wait a day or two before closing/sealing up the hole(s).
As always, apply at label rates and take the label specified safety precautions. Homeowners have a tendency to over apply and interpret straightforward labels in rather creative ways.
UGA or maybe you county ag department should have an extension specialist that can provide more specific information
