Don't you hate that? Everyone's good until you bring in newbies! I've never had bug issues with my birds and I don't like the idea of having them. Ugh! I have dealt with mites and lice on the goats and it is not fun.
Dog Frontline works for mites. It's 2 drops for a silkie and 3 for a regular large fowl. On back between wings, or one there and one above vent. Some people put one under each wing in the armpit and one above vent.
I've only used it when the mites got uncontrollable. That gets expensive really quick. It did save my rooster's life. The stupid little song birds brought in the pests and he very quickly got a horrible infestation that even seven dust and bathing in flea shampoo didn't get rid of. I thought he'd die from the anemia, so went asking on BYC. I dosed everyone and he recovered.