Observation notes: There were four or five clusters of these caterpillars on a witch hazel bush. I have never seen them before and was unable to locate a picture of them online. I am not sure what they are and would appreciate any help you can provide. They were eating the leaves of the witch hazel bush in our backyard and were situated toward the ends of the limbs. I have no idea of they are a stage of a butterfly or are something else. Don't want to harm anything beneficial and am ignorant about caterpillars in general.