>And without a control group, one can't say whether your four treatments >with oxalic vapor were of any benefit in mite control over natural >mortality at that time of year. OK. I see what you are saying here. It _is_ remotely possible that all the oxalic did is accelerate the natural drop and kill mites which would die in the next few days anyhow, resulting in no additional total mite drop over what would have occurred naturally. Having some untreated hives to compare would be valuable to prove that the oxalic resulted in increased mite mortality. Given the variability I demonstrated , I wonder how many controls it would have taken, and would we take the average, or track each control hive? Interesting as that could be, that takes me far from where I was going. Proving that oxalic evaporation kills more mites than using nothing was not my purpose. I think others have proven that conclusively enough for me. What I did was merely record observations of my treatments and the after effects on each of six hives, and share that detail FWIW. I also made note of the young mites dropping and suggested that they are an indicator of emerging brood in hives with non-zero mite loads, and that this could be used to predict the efficacy of treatment -- or not -- since presence of brood is known to reduce efficacy. So, given that I accepted that evaporating oxalic acid in hives kills plenty of mites, my contribution was recording the variation from the mean that is commonly presented, and thus showing how the response is highly variable between hives. The interesting thing is that regardless of the variation in magnitude and timing of the kill -- it is beginning to appear -- the end result is decent control in my situation -- if multiple applications are used. *********************************************** The BEE-L mailing list is powered by L-Soft's renowned LISTSERV(R) list management software. For more information, go to: http://www.lsoft.com/LISTSERV-powered.html Guidelines for posting to BEE-L can be found at: http://honeybeeworld.com/bee-l/guidelines.htm