We have dabbled with Thymol treatments over the past 3 years in conjunction with Formic treatments, and lately, oxalic acid dribble. They all seem to work if applied at the right temperatures and intervals. Sometimes I don't get to dig into the hives after the treatments and inspect the bees thoroughly as I would like, as there is so much to do in so little time. We are treating so often with different treatments I often wondered how some beeks do sticking with just one treatment, such as Thymol.
I was just talking to my friend Steve Cantu from Zolfo Springs, Florida and he mentioned that he has *only* used Thymol treatments with a recipe I gave him that another friend (Chris Werner from Indian Summer Honey Farms) gave me. The application consists of Thymol mixed in warmed Crisco with some additional essential oils added, such as Tea Tree, Eucalyptus and blended with powdered sugar with a geared down drill motor and a paddle until a frosting thickness is attained. We generally apply it in the back corners with a hive tool. He has been successful and has not used any "hard" miticides for about 2 plus years. Steve runs a fair number of hives in Florida, sends quite a few to Cal. for almonds and then pollinates Cukes in Michigan.