I think if it's big (13 mm or more) and dark green, then it is either Nezara or Acrosternum. (Was your bug large? It looks quite large and dark green in the photo.) According to Slater, of the big green dudes, if the scent gland "channel" extends more than halfway out to the edge, and it pointy, then it is Acrosternum. Your photo shows that character for sure. Range may be a key, too, I don't think Nezara is found up into New England--at least Slater says Nezara is only common in the southeast and west to Texas. It's not even too common down here--at least compared to A. hilare.

Now there are, according to Slater, two eastern Acrosternum, and they can be told apart by the border of the pronotum--rather straight in hilare, and sharply curved in A. pennsylvanicum. That can be seen in your photo, and it looks very straight, favoring hilare. I'd like to see a photo of pennsylvanicum to verify this.

Here's my photo of what I am pretty darn sure is Acrosternum hilare for reference:



The usual disclaimer: I'm just trying to apply what I read in the one reference book--Slater (1)--that goes into this much detail. I'm also looking at regional lists for my state for the plausibility factor. I'm always ready to stand corrected.

Patrick Coin
Durham, North Carolina

Hey Patrick,

Well at least I can remove Nezara off of my list, that's a good start:)

I looked at the other shot of this critter, and I see the edge you were talking about. I wonder about this one that was shot in the same area, though it's wing markings seem a bit more defined:


I'll move these images to A. hilare for now...like you, I am always open for corrections.