What Are These Small Green Worms In My Trees?

The small green worms you find in your trees are called cankerworms.

These little caterpillars overwinter as eggs in the tops of shade trees. They typically hatch at the end of March-early April and begin feeding. They primarily feed on Oaks and Maples, however they can be found on flowering ornamentals such as Cherry, Crabapple, and Plums. They do emerge in large enough populations to defoliate trees, however in most cases the tree will push out new leaves and buds. Rarely is it worth trying to control these little worms as they only feed for a couple of weeks and the trees tend to recover completely.