errrmmm, looks like i'll be the one to go "offtopic" in a way :P
most of beekeepers here y+use another way in controling varoe. almost everybody beekeep in AÅ½ 10 frame hives. from 10 frames-combs in the hive we take one out..beeh i've complicated. instead of putting 10 full foundations we put 9,5 if you understand. bees tend to build drone cells in unfounded areas. when drones are capped and you can see that they're big, you cut out all the drone cells with which you remove quite a lot of varoa (varoa likes drone cells). this may be done again and again. some say it's very efficient, some say it might cause varoa to concentrate on worker cells.