Rose Slugs are the larvae of Sawflies, a kind of black-and-yellow Wasp. They are pale-green to metallic green, about an inch in length and can be hairy.
Damage
The Sawfly lays its eggs inside of the leaf of a plant. The eggs hatch (resembling small Caterpillars) and begin to dine on the surface of the leaves, leaving holes and window pane-like damage behind, if not outright skeletonizing the leaf. When they are mature, the Rose Slug larvae fall to the ground and burrow into the soil, where they overwinter, emerging in the spring as Sawflies to start the process over again.
Location
Rose Slugs are found on the West Coast, the Midwest, and east of the Mississippi, with the exception of most parts of Florida.
Similar or Related Pests
Caterpillars