I have three birch trees in my front yard that I've been told have a bronze birch borer infestation, based primarily on the presence of numerous holes, each about 6-7 mm wide. There does seem to be some dieback at the crowns, but I don't know enough to tell if this is "normal" or indicates the trees are under severe stress.
Here's a picture of the three trees, you can see quite a bit of debris from the trees on the roof.
A closeup of the trunks near ground level
A detail of the holes, about 10 feet up one of the trunks
Another detail shot, about 15 feet up one of the other trees
Two arborists have said the trees are not salvageable, but I tend to discount "opinions" when there's an inherent conflict of interest (they're dying, and I'll remove them for you for $5000).
Question: Is it time to remove these trees?