Wood Bees “Carpenter Bees” Nasty to get rid of. They come back year after year and more holes only attract more the following spring. And woodpeckers love to eat them. Once they bore into the wood and lay eggs, the woodpeckers will tear the place down getting at the larva.
Get a spray bottle and put dawn dish washing liquid and mix half with water putting more dishwashing liquid then water and spray in the holes where they have been and watch them fall to ground dead !!! and spray surrounding place where they have been .. it really works i live in a log house and they drill holes in my wood and i tried it and i couldnt belive the bees that came out of the hole within minutes and was dead..