Not sure where you're located, but it sounds like a species of apple borers. There are several types, and all can be a big problem. Spraying bottom 3' of trunks every two weeks or so with permethrin seeems to work for me; there may be other more effective approaches. Commercial guys use (or used) "Lorsban" which was persistent pesticide, but I'm not sure it is even sold anymore.Guys, i had one tree break off a few inches under ground. When i pulled it upright, a bunch of earwigs ran out. Another one just died. What the heck?