usually that back feather thing is rooster damage, also might be group molt due to this time of year the lower hours of sunlight can trigger it.
but seriously the lice powder is fairly cheap and it lasts a long long time , its pretty easy to do , rather than chasing them around and catching them, wait till they roost at night I wear a surgical mask, hospitals will give you a handful if you ask ,Just tell them what you are doing and dont want to breath the stuff, they are more than happy to help, and you can wear gloves or not and dump some powder in your hand and quietly rub it down into feathers down to skin , under wings under neath and move on to the next, dont forget a little around the head and under neck. you dont have to do it very often , its pretty much a once a year chore, unless there is a real problem. lots less stress on everyone than trying to catch them.
blue kote will sooth it but wont kill the buggs, they are almost invivble to the eye, plus they can get scabies ect...and that powder will kill anything like that
also change out all of the bedding and dust in there and replace bedding rub it on roosts ect..