At many of the winter conventions I attended, this method of varroa control is considered, and generally disregarded as ineffective, though it is spoken of in polite and cordial terms.  The reasoning goes like this, based on data from those who tested it with actual mite counts.
 
80% of the mites in a colony at any given time will be hiding and mating in the sealed pupal cell.
 
Sugar dusting, at best, will only remove 1/3 of the phoretic/exposed mites.
 
If 20% of the mites are exposed, then a sugar dusting will only remove 1/3 of those or roughly 6% to 7% of the mites.
 
My contention is, that while one application of powdered sugar may only remove 6% of the mites, won't repeated applications continue to take another 6%?  And another 6%?  And another 6%?  Every day new mites come out of the pupal cell and become targets for removal.  And given their exponential growth potential, eliminating 6% today will reduce the number of their offspring later in the fall.
 
Perhaps the real dilemma is in what level the research data is calling "significant." 
 
The counter argument, still very polite and respectful, contends that this method is too labor intensive (which to me is a tacit agreement without actually agreeing with me).  But I would think, for a small producer who likely has more time than a large commercial operator, this method would hold good potential.
 
And I haven't begun to mention Randy's 8-second application techniques.
 
Grant
Jackson, MO


      

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