I have been into antkeeping for a few months and I got my first Formica queen. But I can't find any information of how to keep what I think is Formica subsericea. Unfortunelly I could not get any pictures but it looks exacly like Formica subsericea.
Nice find! They love to eat soft-bodied insects, they hate hard foods of any sort, they enjoy sugary foods like honey, and their growth rate depends on food supply. I would recommend to get liquid feeder for them. They can be polygynous but I would not recommend it. They are fully claustral but it does not hurt to give them a small drop of honey on a piece of parchment paper. They can get to a few thousand workers and are a very hardy species, though they do spray formic acid.