I read on someone's personal website that a fun game for rats that they seem to love is to make a "Dig Box". I have a small shoebox tote handy, and I was thinking of filling it with a little bit of peat moss and decorative pebbles, and throwing a couple of b.dubia roaches in there. Since roach nymphs (usually) dig down, the rats would have to go for them. That way, they can get their digging and exercise while getting a treat in the process. Has anyone ever done this and did the rats seem to enjoy it?