This bug has been reportedly found in the following regions:
Garfield, Arkansas Champaign, Illinois Saint Joseph, Illinois Hollis Center, Maine Uxbridge, Massachusetts Denville, New Jersey Oyster Bay, New York Pottstown, Pennsylvania Wilkes Barre, Pennsylvania Elkton, Virginia
On Aug 27, 2007, claypa from West Pottsgrove, PA (Zone 6b) wrote:
A major insect pest to the various Dogwood trees and shrubs (Cornus). The adults look like wasps, and lay eggs on leaves in early summer. The larvae eat the leaves in late summer and go through several molts with radically different appearances. They spend the winter in decaying wood and emerge as adults in the spring.
I see them on C. sericea (Red Osier Dogwood); haven't noticed them on the trees but they're probably there too. Sawfly larvae always occur in numbers, never singly, but they're easy to remove if you find them. They just curl up and play dead. The later instars make a cottony substance on their skin.
I see them on yellow twig dogwoods as well. I'm told that they don't harm the plant, that they do only cosmetic damage, but they do plenty of that. They can be killed with a soapy spray (just plain dishwash liquid), but it's hard to get them all. They're generally to be found on the undersides of the leaves.