Sure this isn't a male Ceroptres? I am definitely not an expert, wbut we look at a lot of gallers and inquilines in our lab. On this one, the "collar" on the pronotum is wide, so not like a galler, and you can see the little "saddle" on the basal part of the abdomen that is characteristic of this genus. I actually wonder whether any of the adult "Philonix nigra" pictures on BugGuide are actually that species. All of the gallers we rear from Philonix nigra galls are wingless females.

I agree these are inquilines, most likely Ceroptres based on the same characters Andrew said. I've sent this to Denise Montelongo from Andy Deans' lab, she's working on P. nigra community and should have high quality photos of all the gall inhabitants.