Before I resided my house in vinyl I had the same problem. Only on one side, the north wall which happens to be my bedroom. Sleeping in late one Saturday I'm woken by constant tapping on my wall. I go outside to see a woodpecker working on my cedar shake siding. He must have been doing this for many days when I was at work because while shoeing him away I noticed dozens of holes. He would get through the siding and hit the sheathing and stop, then move to a different spot. Yikes! When I installed new siding there were no signs of any insects. Guessing he liked the smell of the cedar.
