Mites drown in water, if my guess is correct the importing from the US to communist China is a problem. Soaking in soapy water with intensive enclosure cleaning and the surrounding area. Mites drown and adults need to lay eggs if you drown the adults and kill all the eggs and adults and make sure that they cannot return will get rid of all the mites. It takes a lot of work and effort everyday with out fail. Remember let things dry out some Mites NEED water the snake can manage in drier than normal conditions for the 7 day life cycle of a mite.
Permethrin is a poison, it works but if you can only get higher % than 0.5% you run a serious risk of poisoning the animal. If you cannot get P-A-M and do not have the correct instructions ask before you use it to get exact instructions here. I have seen lice treatment s in Turkey that were 8% Permethrin so be very very careful that you do not have anything that strong! Check the label carefully!!!