Charley, I kept them, as you suggested all winter spring, in my shed but its seems to me that they dried up and were not going to hatch so last week end I threw the leaf they were on into the forest.It has been dry and hot so maybe the shed was too dry?

but sometimes cynipids can be dormant for several years before emerging. I have lots of old, dry galls, and every once in a while something emerges from one of them.

Charley,We have already had two mornings of frost last week where temps. were -2C. Daily fluctuations are ranging between -2 and +20 Celsius. Snow could fly in a few weeks and they say it will be deep this year though perhaps mild.
How would I keep it over the winter if I did find it? It's covering seemed thick and I assumed it would drop to the ground with the leaf. On the other hand some Oak leaves turn brown and can hang on trees till spring????
I will try and find one when I return to the lake this week end. If I do, how do you suggest it be cared for?

I keep my overwintering galls in my garage by a window--where they are exposed to the temperatures of winter, and get indirect sunlight through the window, so they can be exposed to changing day lengths if they need that too. Adults would most likely emerge in spring or early summer, though individuals of some species can remain dormant for a year or more. Note that if you did get adults, you would need to send them to a specialist for ID--no one ever identifies adult cynipids on BugGuide, and it probably isn't possible to get to species from photos. I would suggest collecting a good number of galls rather than one, since the majority of galls tend to be parasitized, but if you only found a few it would still be worth giving it a shot. Good luck!