I have never used the spry version yet however, I have used the shampoo for these pests. I first used RID Lice Shampoo for mites in 1997. After a sever case of mites I got from live feeder rodents, I had to erradicate them from my entire collection which at the time consisted of several boas, some green tree pythons, a couple of kingsnkes and a couple of cornsnakes. After several trials with the shampoo to determine the strength that I wanted, I came up with a solution of 50 dorps of RID to 16oz of semi-warm water. I applied this directy to the snakes working against the scales (do not leave it on them for more than five minutes as I mistakenly did the first time) and then rinse the snakes down. The solution can also be used to spray down the enclosure and then wiped out with a dry cloth. Ir you are using newspaper, you can apply a fine mist of the spray between one of the layers before you put the snakes back into their enclosure. This worked great and I was clear of the mites after two applications. You can also use this solution or make it stronger to spray the floor and other areas around your cages to kill off any mites that are hiding outside the enclosures (I strongly recommended you get these area around your enclosure as well since mites are know to pack up and travel across rooms).
Chris