Ok, this a reply to the aspen shavings and pine shavings. I also noticed that someone mentioned wood chips. I know everyone has their own favorite to use and I do not in anyway discourage the use of it if it is non-harmful to the animals as far as oil toxins or any other toxins go. My experience with wood chips was a one time experience. I had a macklots python and decided to try the chips because someone at the petsore recomended it. It wasn't very long after that he started to shed and was using the side of the cage as leverage and a chip got stuck between him and the cage. Lets just say it punctured his side. I wasn't to happy to say the least. Not to say it was a bad substrate, but often times it takes only one time for something to happen and you don't want to take a chance on it happening again. Aspen is a good substrate to use, but along with many of the other wood substrates out there it can harbor pesky unwated mites. We all know that routine. I prefer the substrate that comes in a compacted square. You take it, place it in water, watch it expand and distribute in the cage. It still comes with the chance of harboring mites, but I like it. Other than that I would suggest, aspen, newspaper (inexpensive and easy to clean, but not aesthetically pleasing) or paper towels (same as newspaper). Ultimately, you are the one responsible for your reptile and the one who decides what works for him/her and you.