Oh I don't know. I remember reading somewhere in a site about when doing a powdered sugar dusting, just to take a couple of handfuls of sugar and dump it all over the frames, it is like an avalanche and really causes the bees to become agitated and groom like crazy.
I used a flour sifter to start with, because I thought that would be most efficient. By the time I had gotten well into the treatment, I got fed up with squeezing the handle on the sifter and did what I remembered reading about. Taking it by the handful (my hands are actually quite small, if someone has big hands, I would suggest a smaller handful, hee, hee) and spreading it on the bees that way. It was about 50 times faster than using the flour sifter and it worked pretty darn good. The mite fall on the sticky boards I put in later on were decently significant.
I had newspaper under the colonies to catch the majority of the powdered sugar firstly and I removed that -- and then I put in the sticky boards. I caught the majority of the sugar on the newspaper because I didn't want to leave remenants of powdered sugar in great numbers around the colonies, messy, attracting ants and the like. Beautiful and wonderfully great day, Cindi