There is typically one generation of these insects annually with most of the activity in the Spring. These bees are known to return to previously used galleries from year to year although other bees can make new galleries as well. Some people don't mind these insect that much. As with other bees, they are beneficial as pollinators of flowers. However, other people are not as happy to have carpenter bees around and seek ways to eliminate the bees.
Exclusion is done by sealing and then painting the wood surfaces well.
A good enamel or polyurethane is probably most durable and least likely to be attacked again. Another solution is to wrap exposed wood with aluminum flashing in areas such as the gutter fascia. The most effective pesticide application for existing, active Carpenter Bee galleries is dust. There are several products on the market for this pest. We sell Apicide , a carbaryl dust product and Borid Turbo for those wishing to treat the problem with pesticides.