Dave I might make a few people mad. Powder sugar does make the bees clean themselves. The main reason it helps is because it stops the queen from laying and the bees clean out all the brood. This is why I will not sugar the hive. I will treat with other methods such as thymol, or requeen with better genetics. I recieved a few packages last year, after a few months they had mites. I breed for genetics. I pinched the head and added a VSH Carniolan. The mites level droped in half in 4 weeks and to zero in 6 weeks. There are many ways to deal with mites. I just think powder sugar is not the best option. I have seen people treat just to treat and kill off the hive. The queen will swarm and you will need to requeen. Hope this helps.