There is little you can do about this. Woodpeckers will excavate wood
houses if there is a shortage of tall snags around to do their thing. One
long-term solution is to leave dead snags around rather then cutting them
down. Even in an area with lots of dead snags, if a woodpecker takes a
shine to your house it's hard to discourage them. Sometimes, they just like
the sound of whatever they're pecking at. Or the wood on your house may be
softer and easier to make holes in than the trees around. My husband's
family had a cabin in the Tehachapi mountains in California and the acorn
woodpeckers made so many holes in it that the siding just had to be replaced
every so often. Nothing they tried worked. I kind of like the sound of a
woodpecker pecking, myself. Of course, ours aren't quite this destructive!

Teresa Michelsen
temi461 at ecy.wa.gov