This critter was feeding at the base of palustris needles about 6' off the ground. When I plucked it off gobs of green goo gushed out of its backend! I moved it onto an invasive, non-native for the rest of its meal. This caterpillar was stocky and about 4 inches long, very robust looking! Requesting an ID there doesn't seem to be any need for management.
Thanks to a quick search at Garden Forum I have learned that this critter is the larvae of the Imperial Moth, Eacles imperialis.
