This is an impressively large nymph, quite unusual looking. It didn't want its photo taken and immediately began moving away, so I only got a few not great shots. I post it because I have no other photos of this type of nymph. This is most likely A. terminalis, but as I am not 100% sure, I'll leave it at the Genus level.

To see a photo of an adult in this Genus: http://www.pbase.com/laroseforest/image/145816233