I like provent a mite. same active ingreadient as in nix and i think it's black flag. instead of being a liquid it's a vapour and is far more effective. it's so effective that YOU DO NOT TREAT THE SNAKE, you treat the enclosure. This is great for when the mites are coming from somewhere else, such as your substrate. It's availble at many herp shops and pet stores. while treating the enclosure i like to let the snake soak for a bit.
If you do go the way of provent a mite read the directions 3 times.