I think SB has some good points of reference to research and/or work from. He obviously will choose, test and gage which one worked best for his environment! One last thing, start your treatment processes soon before it gets warmer! Good luck .
Some great info on getting rid of these little guys.Now for a simple check to see how much you've got it under control,find nice clean,white chickens of any breed,place them in the suspect pen.Then check them on a few occasions about ten minutes after they roost.It will be much easier spot the little guys as they journey out of their hiding places and trek up along the chickens legs in a grey color and returning with a much better complexion of bright pink after their supper.
Guys just a FYI. Mites are related to spiders and anything that can kill spiders works well from what I have used. Side note they are very resilient to most pesticides. If you see them make sure you soak them with the pesticide you are using. I couldn't find any Neem oil where I am at but I used the Raid Multi Insect Killer. This stuff works its like using a .22 and switching over to a .45 caliber (and yes it kill spiders, fleas, scorpions too) and kills instantly. I've tried other brands but this one packs a punch. Also, when you have mites and you are overrun with them you will find all various sizes which means they are constantly reproducing at different stages and the possibility of them reproducing everyday is astronomical. By the way they will lay eggs anywhere where they have been and that means everywhere which could be any possibility within a radius of where you have seen them. I know they have laid eggs up in the ceilings of my coops because at night you can feel the baby mites actually dispersing from a top and crawling on your head. Adults don't usually disperse like this but the babies do. When you spray them spray them good and soak everything where you have seen them because they don't all come out to feed at the same time. Those mites that you miss will come out later and they won't stick around they will migrate to another hunting ground that very night so if you see them you need to take care of it right away because they might not be there the next day (especially if you have reduced or removed your birds from that area). I can attest that while lime does not cure, stop, or kill the poultry mites they do help with making their environment less hospitable. They actually have a harder time finding food plotting through this stuff but eventually they will find your birds, its just a matter of time.
As of current I have controlled the numbers way down to only finding a few stragglers here and there at night. Friends day and night is the best time to get them. Night when most and all come out to feed and Day when you find their hiding spots. But if you are overrun you will find them roaming around day or night. So far the best method if you are overrun is to take care of business everyday, day or night. So far its paying off.