I have read all the posts below and I agree with Gaboonkeeper. But I believe 90 degs is to hot for Bitis nasicornis. I go 78 to 82. I put cypress mulch under about a quarter of the enclosure where the hide is and mist the cage three times a week. They are highly susceptible to respiratory problems as well as belly sores from to much or to little moisture. I feed f/t rodents on the side with no mulch and have no problems. Mine never really burrow into the mulch, they just hang out. One last note. Be sure to use a hook and show them where the water bowl is two or three times a week. They can`t seem to find water on there own. Good luck. Bill P.