"Herpivory"? "Ranophagy"? Hurry, I need to mock a French friend.
I guess that would be a ranaphagy, from family Ranidae (true frogs), most of the edible ones being genus Rana.
I think calling him a ranophage sounds better though.
Here's a link mentioning edibility of a couple of species. It ain't just the Frogs wot eat frogs. Apparently them damned Yankees eat even more! (or maybe I should say 'damned Confederacy Southerners')