Last week, I received a text from my friend, Sue Keys, accompanied by several photos of a section of tree trunk bearing rows of unusual whitish wounds or scars. “Can you please tell me who to ask/send these to?” Sue wrote. The tree, a 15-year-old Japanese maple, obviously is suffering from attack by some unknown critter that penetrates the bark. I immediately ruled out rabbit damage, although rabbits and rodents will chew through a tree’s bark to reach the cambium, or growth layer, during the winter when food is scarce. If the rabbit or rodent removes the bark all the way around the tree, the tree may die. From the height of the bark damage in some of the photos, I determined that the culprit would have to be a very tall rabbit.

My next thought was that the damage was caused by a yellow-bellied sap-sucker (Sphyrapicus varius), a member of the woodpecker family. I knew that sapsuckers drill into tree trunks in neat, horizontal rows, but the damage I had observed showed smaller, deep...