When to treat for IPM is also dependent on the area. In east TN, we can treat in July, as there is a general dearth (unless moving to the mountains for sourwood), so we can tolerate a higher spring level. On the other hand, if you treat for spring, you have to start in Jan in order to get the medications off in time for the early spring flow (which can start in March). One reason that the Ag Extension schedules for crop farmers have been so popular is that it requires less thinking on the part of the one doing the application -- just spray when the calendar tells you to. It requires more education (and risk tolerance) to actually assess your pest levels and only treat when "needed". And the whole time youare figuring out those perfect balance levels, you are losing more of your crop than others (although perhaps making more money overall -- something so many seem to have trouble distinguishing). -----Original Message----- From: Peter Borst If 50 (20%) turns into full blown varroa infestation by August, one cannot skip treatment of some type on this hive. This is not a job for statisticians, its a trial and error process.