Ok the spray? DW was thinkin bathing them with the baby shampoo and then dusting them after they dry... i was going to dust the pens thuroughly(SPELL CHECK!) This weekend anyway but you said the DE wont kill the mites? Fudge! What about soapy water? Guess im goin off to the feed store....
the mites can get into every crack and crevice of the coop.. I have heard of people on here who had to burn their coops because they couldn't get rid of them..
here are a few links:
https://www.backyardchickens.com/a/mites-chicken-pests-how-to-protect-your-chickens-from-mites
https://www.backyardchickens.com/t/624059/getting-rid-of-mites-naturally
even once you kill the adults you're going to have to retreat to get any new ones that have hatched..