What you're using is NOT working. Just another bogus product that doesn't do what it claims. I recommend NO-PEST STRIP. This product releases a vapor containing the active ingredient dichlorvos which is HIGHLY effective in killing all stages of mites OVERNIGHT when you use fresh product. Many mail-order co's that sell dry-goods will have this in stock, or your local ACE hardware, Menards, etc., may still have it in stock altho it's out of season.
You'll need to cut an appropriate-sized piece from the strip with a razor blade (about 1.5"x1.5" for a 4'x2'x2' cage, or about 1"x1" for a 15 gallon tank). Put it in a deli cup with about 12-15 1/4" holes in it. Treat for about 12 hours, and repeat every 7-10 days for another 3 treatments.
Make sure there's fresh water available in a container large enough for the snake to submerge in. No dichlorvos does NOT concentrate in the water, despite popular myth.
Some of the popular sprays (Black Knight, Provent-a-mite, etc.) also work but no more effectively then No-Pest strip, IMHO.
These directions apply to most boid snakes only and may need to be modified for other snake families.
Mites are bad news (vectors for bacterial and viral disease, such as IBD). I don't subscribe to half measures when it comes to treatment.
Good luck! Scott J. Michaels DVM