I have been wanting to see this unusual and (to my eye) very beautiful little caterpillar for a long, long time. I have turned over countless thousands of leaves, especially of oak and basswood, at this time of year and no luck until today at Reveler CA. They are very tiny, very flat, very un-caterpillar like. This was on a basswood. A little later I found a second one on red oak. The head is at the bottom, fringed in red.