carpenter bees are extremely tenacious insects, that are attracted to raw wood. painting the wood with oil base paints, several coats, after you have treated the holes in the wood with a residual dust labeled for carpenter bees, and also plugging the holes may deter them until the paint wears, when you will need to re-apply more paint. of course, through all this you are removing that wonderful raw wood look that appeals to you and the bees. when treating the holes, do it at night, they will all be in there, just like honeybees in their hives. Another option would be to let them do their thing and then replace whatever they're infesting with treated wood. In viewing wooden overhangs over the last 15 yrs, while conducting wood destroying insect reports, I rarely see carpenter bee evidence in good quality treated lumber.