It seems the infestation level (mite load) at which treatment should be applied has changed over the years. The information depends on the time of season, migratory or stationary operation and the county or country giving the recommendation. I've read in the past that if you have a 10% mite load (adjusted for mites under cappings, not just mites on bees) you should be treating. The information I've come across lately has a much lower threshold for treatment, in the 2-3% range (adjusted for brood mite load). In a perfect world we would endevor to always keep the mite load as low as possible, but in the real world at what mite load do you feel the need to take action? 1%, 2%, 5%? Spring, summer, fall treatments and loads.