While hunting caterpillars in mid-September. I found this sawfly larvae in the middle of the Kaintuck Hollow Fen in Phelps County. This might be in the Nematus genus as this group feeds a lot on willows. It wasn’t until I looked closely at the photo much later that I noticed it was being parasitized by a small wasp. I would have loved to have gotten a closer photo of the wasp.
A Thousand Acres of Silphiums 