Jorn said: Formic acid is of course an aggressive treatment, killing the Varroa because of their thinner skeleton. Opposite to oxalic acid it also kills Varroa in the capped cells. There were reports of varroa kills in capped cells when beekeepers were using 85% formic but were also many brood and queen kills which is why beekeepers went to the lower percent. I have attended many formic acid talks over the last few years and have not heard the claim formic acid clears varroa out of capped cells made. I do remember hearing claims of clearing varroa from capped cells on the internet years ago. Most beekeepers now use a 65% formic which I have been told does not kill varroa in capped cells but could be wrong as I do not use formic and am going by what others have said to me. Does 65% formic acid kill varroa in capped cells ? I have been told by Bill R. that if you do not get a certain amount of brood kill the formic dose is not strong enough clear a hive of varroa which is why I doubted the efficacy of the formic acid gel from the start. Efficacy with formic acid is nowhere near the efficacy of chemical strips (98%) research has shown as too many variables exist (temp , humidity & dosage which is hard to figure out ) . Bob :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: -- Visit www.honeybeeworld.com/BEE-L for rules, FAQ and other info --- ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::