Answer: Unfortunately, based on the description of the holes and sawdust, I am unable to make a definite identification of the cause of them. There are assorted borers and other insects that will occasionally make holes in trees, there are also birds that may do this in search of insects. You might want to consult with a professionally trained arborist and/or with your county extension (696-3500) about the trees. I'm sorry I can't be more helpful.
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