Perhaps the reason for using powdered sugar for Terra dusting is that it is
similar in consistency to the TM powder itself, and this allows for a
better homogenous application.  This is only a guess.
 
I have always just kept to the granulated sugar for grease/TM patties, but
wonder if the bees would consume it just as quickly in a patty with
powdered sugar.  Anyone tried both, and ever noticed any difference?