Sounds fairly safe I guess, I might try something like theat if I get these ants, maybe with higher sides though (so I can fit taller rocks and sticks).
Noma have you ever had any winged reproductives produced with the Polyrhachis Dives & if so was it seasonal?
At the moment, my colony produces many virgin queens und also males. It does not seem to be seasonal.
I think, they produce them when they reach a certain colony size (>200) and when they can effort it. That means when they get enough food. They started to produce males earlier, i guess when there were more than 100 workers. By the way, my colony (only) has one queen.
I posted some pictures in the thread already linked above.