Oftentimes, when describing signs of insect infestation in trees, the exit hole is used as a diagnostic character. Is it D-shaped? It might be emerald ash borer. Does it look like the tree was shot with a shotgun? Might be bark beetles. These holes are created when a pest emerges from the tree. But what if the holes on the tree are from something trying to get in, instead of out?
Image by Randy Cyr, Greentree, Bugwood.org.
One animal in particular is known for its characteristic holes, drilled in horizontal lines in the trunks of trees. It raises questions and is often confused with insect damage. But it is caused by something much larger and much more feathery than insects: the yellow-bellied sapsucker. Like insect exit holes, the holes this bird creates are indicative of what caused them, even if the animal itself is absent.
Making more holes than a pro golfer, yellow-bellied sapsuckers are a type of woodpecker that drill holes in living trees, eating the sap and the insects drawn to the sap. They enjoy the buffet the forest provides, feeding on more than 250 tree and woody plant species.
Typically, the holes they cause does not cause enough damage to severely injure or kill the tree and therefore does not warrant control. Even if you wanted to, yellow-bellied sapsuckers are migratory birds and are thus protected by the Migratory Bird Treaty Act. The holes provide more of a curiosity than anything else!