The woodpecker that makes these holes does not drill seeking insects under the bark, and despite the sometimes extensive pecking, they do not usually cause serious damage to a tree. This is the work of a Yellow-bellied Sapsucker, a native bird that overwinters in our area but which breeds in the summer further north (or up in the mountains in our western counties). They feed on sap that oozes from the holes, or potentially also on insects (in mild temperatures) that are attracted to the oozing sap. Migrating Ruby-throated Hummingbirds and some of our earliest-flying butterflies use these important sources of sugar as food in early spring. You can learn more and view some images of their two styles of pecking (horizontal rows of round holes and a lace-like pattern of more shallow, square holes) in the linked pages. Nothing needs to be done -- nor would any intervention to try to discourage the bird be likely to work well -- about the bark holes, which should become less obvious as the tree ages.

Miri