Here is a link to a video that shows how to use powdered sugar to dust a colony for varroa mite control.
Some equipment needed
Powdered Sugar, 3/4 cup per medium super, 1 cup per deep super
Window screen or flour shifter
Usual hive inspection equipment
Colony must be on a screened bottom board
Current technique is to not break colonies apart but apply appropriate amount of sugar through top super
Notice in video that I forgot to brush sugar off the frame top bars. You need to get the sugar down between the frames!