Mature bark has been peeling off several of my trees - the most concerning are a black pine and a larch. The larch has lost almost all of its flaky bark on its trunk and the black pine has lost all of it on the bottom few inches of the tree. I have found what looks like the remains of small cocoons
The larch does not show any signs of sap leakage or other holes in the trunk. And, for now at least, seems healthy and growing vigorously. The black pine is showing white residue that appears to be dried sap but I don’t see any holes in the trunk. The new growth is strong but older needles are yellowing.
My fear is that this is the early signs of borers but I don’t really know. Interested in any thoughts on causes or recommendations on an insecticide that might be broadly useful even in the absence of a specific identification.