Dogwood Sawfly Larvae

I'm happy to help. And I agree--I love how much I can learn from everyone here. For example, a few years ago, local insects were little more than things that got in my way while I was taking pictures of plants. I never thought I could have a reasonable shot at IDing them. Thanks to Project Noah, Bug Guide, etc., a whole new world has opened up for me.

I took the liberty of following up on this on my own. The long petioles, the venation pattern (best seen in the video), and the whitish color to the undersides look like Cornus racemosa, gray dogwood. It doesn't grow in the part of Virginia I live in, so I'm not really familiar with it. It's supposed to grow all over Pennsylvania. Check out http://www.carolinanature.com/trees/cora.html and see if this looks familiar. That site says the leaves look like those of C. amomum, but the petioles of C. amomum are distinctly reddish, not green, and the veins look different to me as they approach the margin. I never meant to suggest that the insect ID was wrong, or that the plant wasn't some kind of dogwood, by the way. Something about the leaves just got stuck in my head.

How unusual for all of those caterpillars to be on the same leaf. Great photo!

Does this species eat anything other than Cornus? The venation of the leaves doesn't look like that of any species of Cornus I know (not that I know them all).

With a bit of help, we (Jakubko) and I were able to narrow it downto M. tarsatus. We are pretty sure this is correct. :)

These are Sawfly larvae (a type of Wasp). They look similar to Macremphytus testaceus (Dogwood Sawfly): http://bugguide.net/node/view/303138

Reminds me of the book ," A very hungry caterpillar" by Eric Carle!! Look how much of the leaf these guys have eaten!!