Found on a witch hazel leaf, but no sign of feeding. Is this a syrphid larva or something? My first impression was of a limacodid, but those two projections seem fly-like. I have the larva and the leaf in a container, but I'm not sure what to do with it... not a very active creature, but it does right itself pretty quickly when I flip it over.

Edit: After initial post, I found these images:

So I guess syrphid is the consensus on things that look like this. I'll see if I can find it some aphids...