Substrates don't "cause" mites. Substrates may make it easier for existing mites to multiply but they won't create them where they don't already exist. Cypress and other wood substrates sometimes carry annoying litle gnats that can explode in the warm and humid environment of a Burmese but since snake mites are generally species specific, it is highly unlikely that your substrate brought snake mites with it (unless you purchased it in a mite infested pet store).
That said, any substrate can create an environment for mites to flourish- there is no mite-proof substrate to my knowledge (wooden cages or wooden shelves, and carpeting also give mites an edge in your environment). You can prevent mite infestations from breaking out in any substrate with Provent-a-Mite. Sprayed on and allowed to dry it kills existing mites and prevents their return for 30 days. If you spot clean areas make sure you spray the new substrate and allow it to dry before you place it in the cage. Choose the substrate you like best and then treat it before you put it in with your snakes- or take the snake out of her cage and treat the substrate, allowing the spray to dry and the fumes to dissipate before returning her.
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Marcia Pimentel
Tango River Reptiles
GiantFeeders