Ok, the web is littered with commentary on red mite and how to deal with it. The crux though in my experience is catching it early. Spot it early on and you have half a chance of defeating it…. let it go unseen and you will rue the day, and so will your chickens.
If you are new to chicken keeping then you may not yet have encountered the poultry keepers Nemesis, the Red Mite. You may however have read all about it and have a good grasp of the pain in the proverbial it can be but unless you have actually witness the cigarette ash like droppings they leave, or that microscopic tickle as they crawl over your arm or through your hair, then you might well not know whether mite is there or not.
So grab a handful of drinking straws, tie them into a bunch and then place them in a dark corner of the coop or nest box. When it comes to mucking out the coop each week remove the straws, blow down them on a piece of white paper and if the resulting detritus gets up and starts walking around then you might have mite to deal with.