This is what i did since i live somewhere without access to ivameticin etc I also have a smaler flock but only had 2 birds infected. other birds didnt have a single bug. They were infected I beleive because they were already weaker and i had exposed them to a slightly damp coop.(its dry now) 1. soaked bird in warm salt water and vinegar 5 mins. hold chicken up to neck. 2. soaked and washed chicken in a tea tree shampoo. dawn soap might work too? held in this solution 5-7 mins. the bugs climb all the way up to their eyes to not drown. i made sure to put soapy water there but not in the eyes. 3. rinse in clean warm water 4. blow dry . can take 45 mins...(warm air not hot) I repeated this step again 48 hours later because the eggs don't all come off in the wash and tiny new bugs were hatching. mites make a horrible mess around the vent primarily. they can also feed near the neck, legs and wings. Where they had made a lot of scabs i put a mixture of coconut oil and a herbal oil i made. Somthing that kills germs and helps heal. i think polysporn does this? i use herbal oil because i want to draw out any infection and not trap anything bad. I fed the girls cooked eggs and made sure they had plenty of water as the mites making them dehydrated. before i put them back in the coop i filled a bag with sand and gave a thorough dusting to them. i have also added apple cider vinegar to th coop water. apparantly it helps prevent bugs. i also sprinkled dried lavender and DE in the coop. 2 weeks now and not a single bug has been seen again.