Sevin dust...hold the bird down (at night is best & wear a dust mask on your face) and dust the bird...rub it in all over them, and repeat on every bird in the coop & do repeat in 6-7 days in cold temps, or 3-4 days in hot days.
GOOP : a tub of Crisco or lard on roosts, I add 3 T of NEEM oil, and 2 T of "Melafix" tea tree oil. in a double boiler, & once cooled, glove up & goop all roosts, ladders & perches.
This "Roost Rub" is also excellent for sore bird feet or scaley leg mites, just rub it in as best you can under the raised scales.
I also load the hudson sprayer with NEEM oil per the directions AND sevin and totally cover the walls, ceiling, nest boxes & you name, every so many days as I said above.
For 3-4 doses. Each dose is the days of separation from one dose to the next, in November, I go 6 days, so every 6 days I do this method.
Never stop watching your birds if they are figety...picking at themselves...never stop grabbing a bird & turning them over to look for bugs.
Make it a habit to go out in your coops at night weekly, and flip a few over & see what is going on at night~~~
you may be very surprised.