Walnut Caterpillar – On Walnut Tree
Q: My husband and I found these worms/caterpillars eating the leaves of a black walnut tree at the edge of our pasture. Later we found the same type of critters devouring the leaves of a black cherry tree. Could these also be army worms?
A: Their eponymous name is walnut caterpillar, Datana integerrima. It is startling to see their gregarious behavior: dozens of them chewing leaf edges or a mass of them crawling on a tree trunk. They defoliate random walnut limbs but they will not kill the plant. You can spray them with insecticide as you see them or simply wait for natural predators to kill them. Hornets and paper wasps find these caterpillars a delicacy.