Because Cypress is way too expensive! I used it for my boa and his cage takes three medium sized bags at $32 each! It is also something I have tried to find in bulk, but because I could not I decided to try the compressed coconut husk, but if it got too wet (say a snake spilled their dish) humidity would rise way to high and I would have to change it out immediately, not to mention super messy. I have tried pretty much everything. I originally wanted to use aspen, because it really is the only one I have not used for my BPs, and of course the pine but it is seriously no where.