A spiny caterpillar – possibly a species of silk moth?
July 3, 2010
I found two of these guys happily munching away on a single beach plum (prunus maritima) in my front yard in Newbury, MA. They are approximately 2 inches long at the moment. I’m thinking they are some sort of silk moth instar, but I can’t find anything quite like them in my books. So naturally – I turned to you folks. Ideas?
Your caterpillar is most definitely one of the Giant Silkmoths. It is the Cecropia Moth Caterpillar, Hyalophora cecropia, and we find it hard to believe that it is not pictured in your identification guides.