Question
I live 30 miles outside of Dallas Tx. I have 3 live oak trees in my yard that are 12 to 15 years old. I have noticed several of the big limbs having several holes about one quarter inch in diameter or smaller that completely ring the limbs and are very close together.  Some have said that it could be wood peckers but I have not seen nor heard any. Could these be some type of borers? I seems that they are starting to affect the condition of my trees. Thank you!

Answer
I tend to agree that it is sapsucker damage (wood peckers). These birds peck holes, similar to a machine gun, in the bark which fill up with sap from the tree --this sap attracks small insects and the birds come back to eat the insects. In a homeowner situation they rarely cause much damge to the point of killing the tree. In a Forest situation the birds do degrade the wood that will make lumber. Sometimes the woodpecker are looking form insects under the bark and will peck large areas of bark off looking for the boring insects. That is not what you discribed. Here is a web link for more information on sapsuckers.  http://www.na.fs.fed.us/spfo/pubs/howtos/ht_sap/sap.htm