Dogwood Sawfly

Notes:

Found feeding on Gray Dogwood, Cornus racemosa. I'd never seen these up until a few weeks ago, but I've now spotted them in two locations 20 miles apart. They look like caterpillars but are the larvae of a sawfly, a wasp-like insect. The powdery white ones are second instar larvae while the black, white and yellow ones are a late molt.