Anyone who might like to see an example of some of the tree boring insects birds will go after. The smaller birds will come behind and feed on some of them, or the sap that seeps out from the opened holes.
Borers like these are found in Fruit trees, Oak, Poplars, Ash, Beech, and numerous other tree species (some others listed here.. this is only two of many similar pages in this book).
So when you see a Woodpecker or larger birds pecking madly at the branch on your trees, this might be what they are after... Maintaining in places we can not reach, they are able to sense the activity of beetles and larvae deep inside the branches, saving the trees and getting a nice meal for their hard work.
You might be able to read some of the info here from the book, Ultimate Guide to Backyard Bugs, Garden Insects of North America.
~debnes
