"Would it not be wise, for him, to bring the hives up north to stop the brood rearing. At that point treat with oxalic while the hives are broodless??" This is what I would do. I would stay, and use the trickle method. This has effect 2 to 3 weeks. Works slower and longer then the vaporizing method. Remember worker brood is 12 days closed and drone brood 16 days. The Varoa on the bees are killed in 2-7 days. The oxalic will overlap a important part of the closed brood, so it will still kill most of the emerging varoa's. The affect will not be as high as with broodless, but will prevent the colony from collapse. Use for a colony in 2 chambers maximum 50 ml divided over the 2 chambers. Better no honey chambers. Smaller colony's 5 Ml per frame with bees. For very good pictures and explanation: See the site from Gustafson Sweden: http://www.algonet.se/~beeman/index-f.html Click onto research - Varoa. You will be able to read about Formic and Oxalic. and my page: If your interested in the results numbers, and the graphics, visit my site. http://home.hetnet.nl/~kroese/ sub page "Varoa bestrijding" (sorry Dutch language) I will try to translate it in English later. But the numbers and the graphics speak for themselves. Hennie Kroese Netherlands........... :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: -- Visit www.honeybeeworld.com/BEE-L for rules, FAQ and other info --- ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::