We had a late freeze in mid March just after my 3-4 yr old Wonderful and Angel Red poms began to leaf out. The freeze claimed the new tender leaves, and I found ~1inch saggy "thorns" on the trees within a few days that actually were the sawdust "turds" hanging from each hole.
Interestingly, the Sweet pom in the group leafed out just after the freeze, suffered no damage from the freeze (apparently), and was not invaded at all by the borers. None of my citrus/fig/persimmon trees were affected either. These guys must be attracted to plants under stress. I remain surprised that they are that selective.
I pulled the Wonderful (wasn't) and trimmed the AR (jury still out on whether this one is a keeper), though both had shown re-emergence throughout the trees, including the bored branches, beforehand.
What is the natural history of disease for the borers? Are the affected trunks destined to die, or are they merely hosts? Is it dependant on the type of tree, or type of borer?
I took some pics of the trunks with the sawdust that I will post when I get the chance.