Red Mite problems are quite common with Chicken Keepers, especially in the drier month's when temperatures give them better scope to survive.
It is also known that Mites prefer wooden sheds to plastic, especially when there are lots of nooks and crannies for them to breed in.
The first signs of a Mite problem are quite obvious, the Chickens start scratching and can get very lethargic and off colour. I regret to say that often, after you've been in the Chicken House, you may find yourself scratching a bit as well, all be it, they don't like humans so much and will eventually work their way off.
I get into the habit of always showering immediately after cleaning out the House.
You can identify Red Mite only through close inspection. Favourite places are at the end of perches and in any dry corner of the Shed.
Most treatments are pretty straight forward, but always read the instructions carefully.