I am still convinced as was Brother Adam that resistance to tracheal mites can be selected for. A 20% loss is acceptable to me and is easily recovered from by pulling a few frames here and there from the survivors which also helps with swarm control. If my losses mount to a leval higher than I can accept I will resort to treatments or preventatives. If 95 % of the bees perished when acarine first came around then I want my bees from the 5% that survived. I am not convinced that the solution comes from a packet a strip a crisco can or the laboratory.