My rescue BP has mites too. I live in England, UK and our reptile vet recommended Frontline (yes the Frontline flea spray you get for cats and dogs).

We can't get Provent-a-Mite here although I've sent to the States to try and get it (hopefully it'll get through Customs).

What the vet told me to do with the Frontline was wear a pair or rubber gloves, spray the gloves and gently stroke the snake, over it's back, under it's belly, right down to it's tail but avoid the eyes and mouth. I avoided the head altogether. While the snake is out of the viv, thoroughly clean the viv and all accessories (even the artificial leaves and plants, hides etc). I used a Polti Steam Gun which pumps out steam at 300 deg F, then spray the inside of the viv with Frontline, leave the doors open and let it dry thoroughly so there's no fumes left before returning the snakes and their accessories back into their viv. Also remove their normal sized drinking water bowl and replace it with a small one so they can't sit in it. If they sit in their water bowl, then drink from it after they've been Frontlined, they can get poisoned by the tainted water, so just use a small bowl. I'm using a small ramekin dish so the snake can't sit in it but they can drink from it OK.

Then repeat the whole process 14 days after the first - this is to kill any mites that may have hatched out in that time as Frontline will kill the mites but not any eggs they've laid.

I would also say, if anyone is going to use Frontline in the States, please check the ingredients as they may differ slightly to ours in the UK. There could be an ingredient used in the USA version of Frontline that could be harmful to snakes. We are governed by EEC regulations (which suck at the best of times) so there could be a variance. It would also be wise the check if you can use it with a reputable reptile vet.

Hope this helps.