Every storm that blows through knocks down a few trees on my property. Usually, an examination of the point of fracture reveals that the tree had been weakened by carpenter ants; much of the inside was hollowed out and filled with sawdust. So I’m wondering, if ants or other insects hollow out a section of tree, then move out or die for some reason, is that tree forever weakened in those areas, or will it “heal” itself over time?
Yes, that’s correct. The only part of a tree trunk that is alive is a relatively thin layer located between the bark and the heartwood. The rest is dead tissue and the tree cannot repair it if it rots away or is riddled by insects. However, if there is a wound that just penetrates the outer part of the tree, the growing layer of the tree (the cambium) can grow over it and “'heal” it.