Okay you have to be really careful about green tree pythons and mites because almost all mite medication dries them out and YOU DO NOT WANT THAT for an animal that thrives in humidity!
The best thing to do is to get a box of NIX lice treatment and mix it in one gallon of distilled water! MIX IT VERY WELL!
First remove the snake and put him in a tub and spray him very heavily with the nix solution, yes you can spray his face as this is going to be very diluted and will not harm the snake. Let him sit in the tub covered in the solution for about an hour! While he is soaking, you scrub everything in his cage from top to bottom! And the outside of the cage too! And about 5 feet around the cage. Mites can travel and it is definitely a must to treat the other snake and his cage too. If you dont see any mites on him, move him to another room quick but treat him first just in case he is just starting to get them!
After the cage has been cleaned to perfection, spray the nix solution on everthing in the cage, only use white paper towels if possible for the substrate as this will be easy to detect mites and if you have live plants its best to throw them out! You can leave the spray on the stuff in the cage even the walls of the tank.
Rinse the snake with a spray bottle of clean water and put him back in the cage.
Treat the snake weekly until you have not seen mites in 21 days! You can also spray the cage floor every other day and it will just help that much more, just be sure to remove the water dish before you do! Keep a close check on the water dish as you will find dead mites in there usually if they are still present.
You can also use the nix solution from then out on on the floor of the cage each time you clean it as preventative measures.
Mites can come from anything and everything outdoors, branches, grass, plants. You can also get them from beddings you buy in stores or bedding you get from garden centers. If you insist on using substrate other than paper towels or newspaper, you can treat the bedding for mites with the nix solution, or if you are using eco earth, you can keep the bricks of it in the freezer for a week before you use them. Or if you are using cypress mulch, get you a foil turkey roasting pan and pop you a big pan of the cypress in the oven at 400 for 40 minutes and that will kill anything!
You may want to google snake mites and read up about them. They can be very hard to get rid of so its important you keep treating the snake and the tank for at least 21 days after the last mite has been seen.
Good luck!
