I recently attended a speech presented by Michael and Kirsten Traynor on the topic of Organic Varroa control. One of their treatment methods involved using oxalic acid on the winter cluster to kill the mites. I was wondering if anyone here has experience using this or opinions about it? Also, does anybody know how it kills the mites? They didn't have enough time to expound on this method and I am still very curious as to how it works and the pro's and con's of using it.