Q.Do termites and carpenter ants kill living trees
I have a very old and large White Alder, trunk 13 feet around, in my backyard. It has been healthy, but recently has developed a lot of dying limbs and there is loose bark forming along one side of the trunk, but at least 3/4 of the bark still looks healthy and has green limbs above it. I was told that termites and carpenter ants may be killing the tree. I have seen neither insect, but there is dry rot leading to a hole in the ground, and some small insect holes under loose bark.
My question: Would these insects attack solid hardwood in the center of the trunk or just move into already rotting wood from some other cause? I have never seen either of these pests bother live trees (in Willamette Valley in Oregon), but know they are fairly common in wood structures and wood in touch with the ground. I am hoping to prune, treat, and fertilize the tree and hope it can make a comeback, if the central core is still in tact to support it. Thank you.
I am not to sure about either, though I do not think ants would pose a serious threat to the tree and termites normally affect trees that are already under stress. It could be tree borers (https://www.gardeningknowhow.com/ornamental/trees/tgen/tree-borer-insects.htm), but to err on the safe side, I would have a tree specialist come out and have a look at it.