I am in west Michigan and found these in the evening on the 15th. They were under/in a small rotting piece of wood. They did not seem to have any sort of entrance to a nest, and I didn't see anything when I dug a little under the piece of wood. I collected all of them I could, but didn't end up with anything that looks like a reproductive. I don't know if maybe the reproductive looks very similar to the workers? Or if they are subterranean and I goofed.
I collected the whole piece of wood they were in. Figured they seemed to like it and if any more were in it I'd play it safe.