Hello Nelsonpitter and welcome to the forum. Potash, or wood ash, is a common treatment against red mite and is the only one available here in France apart from lime wash for the stone coop walls. It is supposed to suffocate red mite and any other bugs on poultry. We use it in conjunction with various chemicals (Nettex total mite kill and Smite), biocides (Elector and barrier spray), a steam cleaner and creosote wood preservative. There is also diatom or diatomaceous earth, which is crushed sea shells. The principle is that the sharp grains cut through the mites' protective surface coating so they dehydrate and die. Red mite can multiply 100 fold in as little as 6 days, as we were reminded the other day! Nothing visible to totally infested in three weeks due to the coop temperatures in the sun rising to over 30 degrees.