Thanks for catching the error. For the life of me, I can't imagine why I would have been so confident (about a nymph, no less) way back in 2014. I guess I'm getting smarter with age. :)

hey it wasn't just you! Nymphs of these two species were misidentified and confused for years on here, and then when I took over and did not know any better, I kept misidentifying them since I was not in a position to question those older IDs. For the last year or two it started to become clear to me that the IDs might not be as correct as we had initially thought, and then Solomon came across a paper that describes the nymphs of both species, which adds a lot of clarity to this issue. Basically, the spotted nymphs are 4th or 5th instars of Flatormenis.
https://www.researchgate.net/publication/233554531_Life_Histories_of_Anormenis_septentrionalis_Metcalfa_pruinosa_and_Ormenoides_venusta_with_Descriptions_of_Immature_Stages


Also, here is a paper that has pics of Metcalfa pruinosa nymphs:
http://delphacid.s3.amazonaws.com/6456.pd

I'll have to check out those links--but I have no plans to place these to species any more. :)