
 Are you sure they don't have mites? First you need to determine if you have mites. Some mites only come out at night to feed on the birds. I use a headlamp so I have both hands free to check over the birds after they roost. I have a lot of birds. I had a mite infestation in one coop but then discovered some in another coop. I thought my birds were molting but they weren't getting their feathers back in. Upon closer inspection I discovered they were loaded with mites. I treated them with DE for a couple of weeks and they still were loaded with mites. I'm not a believer in DE anymore. It certainly didn't work here. I got some permethrin and sprayed the birds and all of the coops well, every crack and crevice, everywhere. After a couple of weeks the birds were looking better and even starting to get their feathers back in. I do 3 or 4 weekly treatments then stop. The mites can get a resistance to it. I do put poultry dust with permethrin in the nest boxes. The bonus is there is no egg withdrawal period and everything is available at 
TSC. I use a garden sprayer because I like the wand to get to hard to reach areas. I also use poultry dust in the nest boxes. Good luck...