This is an older thread but pertinent. To be sure there are no mites check your birds at night after they roost. Some mites only come out at night and feed on the birds. I use a headlamp so I have both of my hands free to inspect the birds. Also you can take a paper towel and bub it on and under the roost and see if you get any streaks, evidence of mites. I use permethrin. It has worked well for me. You can buy the premixed sprays or the concentrate. I use the 0.50% solution of permethrin 10. I use poultry dust in the nest boxes. As a bonus there is no egg withdrawal period. Good luck...
