My mated female, Delilah, started digging like crazy 2 days ago. I first set her up with one bag of moistened vermiculite (Lowes...$5), but that was too shallow...she was not impressed, as it was not deep enough. I then added a second bag in a deeper container. I placed a wine bottle in the laybox, at an angle, and packed the moist vermiculite firmly around it... then removed the bottle...to simulate the shape of a burrow. She was much happier...she went in and inspected...made some modifications, then backed the truck up into it. This morning she had covered the burrow up, and was standing guard. I am a newbie at all of this...and followed the suggestion of some more experienced posters...the pre-burrow idea was a great one for Delilah anyway.