In reading over the Food Grade Mineral Oil (FGMO) archives, and now the screen bottom board treads I have a bit of a question that may apply to any treatment study of the Varroa mites. Since the sticky boards result in dropping mites not being able to make their way back to a host, could some of the positive results found in some studies be the result of the presense of the sticky boards, and have nothing to do with the treatment being studied? Add to the question the fact that some (if not all) smoker fuels cause some degree of mite drop. The colonies being used for a test may be coming under more frequent manipulations, which require smoke, to add and remove the sticky boards.