Quite often I get sent pictures to identify, ranging from birds, trees, bugs and everything in between. I got one last week that had me stumped for a bit but the answer was quite interesting. The picture was of squares cut or chewed into the bark on a small tree. This Nine Minute Naturalist will unwrap the mystery of this particular bark damage phenomena.

Bark damage

The series of squares cut into the bark of the tree were a result of two different attacks on the bark. The initial wound in the bark is a result of a wary feathered friend of ours the yellow-bellied sapsucker. This migratory bird, that spends its winter in Virginia, feeds primarily on sap from over 1000 variety of woody plants. Their search for sap results in an organized line of sapwells easily recognized from a distance. The sapsucker licks the sap and feeds on the cambium of the tree as well. They sometimes create rectangular holes which must be maintained continually to use as a food source. Their preferred trees are maples and birches. Their sapwells rarely cause long-term damage but have been known to girdle smaller woody plants.

Yellow-bellied sapsucker

The second source of damage is attracted to the flowing sap. The wound in the tree attracts hornets that enlarge the holes in search of cellulose to increase their nests. The common culprit in our area is the European hornet, which was introduced in North America around 200 years ago. This large hornet is primarily nocturnal and is rarely seen causing damage in the daylight. Once night falls, the workers emerge from their hidden nests to collect cellulose or food such as crickets, grasshoppers, bees, flies and caterpillars. Another culprit is the bald-faced hornet. These large paper wasps create giant cardboard nests in trees and can be aggressive protectors of their nest area. This black and white patterned wasp is active in the daytime hours and can be seen actively stripping bark to get at the cambium layer for nesting materials.

Bald-faced hornet

Many problems such as this bark damage or diseases such as beech bark disease are complexes, meaning it is a combination of factors that cause the particular problem. So often in the natural world factors work together for good or bad results. In this case we have different species attacking two different parts of the tree to cause damage. The next time you wander the woods at Wintergreen make sure you impress your hiking partner with your knowledge of the natural world.