Ron, As you say - 100% kill of Varroa mites by methods accepted is not realistic. Your logic is to kill those that are "in the open" - therefore reducing the period of time that a pesticide is being applied in the hive environment. This then possibly resulting in the amount of material being transferred into the wax medium. Several points: 1. Is the transfer of active material into wax a steady constant, or is a disproportionate amount transferred during the first few days/week a strip is in the hive? 2. Varroa mite kill: What is the proportion of mites outside the brood and open to pesticide contact compared to those being protected by being in a sealed cell environment? It may be interesting to see that for example, 99% of these outside mites drop - but if a high proportion are left, having been shielded in the cells, these then may raise the viable population above a threshold value very quickly after having emerged. Regards, Peter :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: -- Visit www.honeybeeworld.com/BEE-L for rules, FAQ and other info --- ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::