The first and foremost best method of control with carpenter bees is to prevent them from ever infesting a structure.

Using a polyurethane or oil based paint to completely cover any exposed wood is a primary deterrent to the bees. It's important to inspect those surfaces regularly to watch for any deterioration in the painted surfaces. When the paint or coating deteriorates, it leaves exposed wood that the carpenter bees are able to attack.

Wood stains that soak into the wood do not provide a barrier between the carpenter bee and the wood, and are ineffective at stopping carpenter bee infestations.

Another way to prevent and control carpenter bees from entering a structure is to cover it in aluminum, asbestos, asphalt or vinyl siding, or use some other type of non-wood material to prevent the bee from gaining access to the bare wood.

When dealing with carpenter bees that already have excavations established, use daylight hours to locate and mark any tunnel entrances. Treatment should be done in the dark and on an evening when the weather is cool. This means the bees are more sedentary and less likely to be aroused by activity around the holes. However, you should still wear protective clothing so that you can avoid being stung if you disturb any female bees.

Male bees are the ones that are generally more aggressive, but they do not sting. However, if you are disturbing the nest, they will fly aggressively around and dive-bomb you or any moving object that gets close.

Since carpenter bees are wood boring bees one approach to controlling carpenter bees is to seal each entrance hole to their excavations, thereby eliminating their ability to gather food, if they are sealed inside, and cut them off from their home, if they are sealed outside.To do this, mark each entrance that you find. Use a caulking compound of some kind, a wooden dowel also works well covered generously in wood glue, or you can use wood putty. As much as possible, fill the entire excavations with the sealing compound. Use a caulking gun or similar tool to compress the compound into as many of the galleries as possible.

Since the carpenter bees depend on their galleries to survive the winter and need them for protection during the winter, this method can be very effective in reducing or eliminating the population of the group. Because of behavioral conditioning, the bees stuck inside the galleries behind the barriers do not chew their way out a new entrance, and the blocked entrances are a severe deterrent to those trapped outside.

It is also effective to kill the single female, if she can be found in a new nest. You can accomplish this by simply swatting her, or capturing her, or otherwise killing her. If you are attempting to destroy a nest, then try putting a wire into the entrance hole and probe into the excavation, doing this may kill carpenter bee larvae and pupae.

After taking these measures, it's recommended that you also use the sealing method to close off and fill all excavations in the wood. Painting the wood to prevent new excavations is also a good idea.