I recalled seing a study by Adony Melathopoulos and John Gates, so I wrote Adony. Here is what he says. The charts he sent me with more detailed info are at http://www.honeybeeworld.com/adony/ --- begin adony's reply to my query -- It was published in the June issue of ABJ this year. Here is the abstract of the paper: API LIFE VAR and Apiguard were evaluated for their ability to control Varroa mites and for safety to bees following fall treatment of full-sized colonies in two different apiaries in British Columbia, Canada. Colonies treated with API LIFE VAR or Apiguard provided comparable Varroa control to that observed among colonies treated with fluvalinate (Apistan ), a highly-effective Varroa acaricide. API LIFE VAR-treated colonies during the first week of treatment at one apiary, however, had 70% fewer Varroa drop on adhesive boards compared with Apistan-treated colonies. Although Apiguard-treated colonies had similar levels of Varroa drop to those treated with Apistan, they had approximately 40% fewer adult bees and sealed brood in one apiary the spring following treatment. The release rate of all volatile compounds was considerably higher for Apiguard than API LIFE VAR over the first 3 d of treatment, however rates were similar throughout the remaining treatment period, suggesting the release rate of thymol only differs initially between the products. Our results indicate that fall treatments with either API LIFE VAR or Apiguard provide good control of low-level Varroa infestations with limited negative effects on early spring bee population. This fall I am running a slow-release formic acid vs Mite Wipe vs liquid oxalic acid trial. Great weather for formic acid and the 21 day treatment ends this week (I started as soon as the honey supers came off). Good mite infestation for an experiment as well. I will apply the oxalic just before wrapping. Knock what ever remains among the treatments down in May. Adony ..................................................... Adony Melathopoulos, M.P.M. Apiculture Biotechnician / Biotechnicien en Apiculture Agriculture and Agri-Food Canada / Agriculture et Agroalimentaire Canada Telephone / Téléphone: 780-354-5130 Facsimile / Télécopieur: 780-354-8171 P.O. Box 29 / C.P. 29 Beaverlodge, Alberta / Beaverlodge (Alberta) T0H 0C0 Canada [log in to unmask] :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: -- Visit www.honeybeeworld.com/BEE-L for rules, FAQ and other info --- ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::