Watched a presentation from a researcher at Penn State through my bee club today. They took package bees with known varroa and did OA dribble, vapor and spray during install. While all three methods help reduce varroa and there was little difference in build-up between the treated hives and the non treated control hives, when honey was pulled in August the control hives produced almost twice as much honey as the treated hives. Has anyone else noticed this? They did not do a follow-up to try and find out why this happened, it was just what they observed.