Variable oakleaf caterpillar

These caterpillars have a big appetite for oak leaves, but have also been known to eat leaves of beech, basswood, elm, walnut, boxelder, apple and persimmon. This one was making quick work of a young oak and strategically leaving its feces or frass on a leaf seen at the bottom of the picture. I found a fascinating study of caterpillars with regards to their frass and the host plant that they are eating. It can be found in the bottom reference. (Not sure if it applies here, but it is an interesting read).