In experiments measuring the growth of mite populations in colonies  
started with equal number of mites, it is not uncommon to find many- 
fold differences between colonies tested at the end of two to three  
months of good conditions (with no robbing and little drift?).  The  
assumption is that these differences are primarily from ways in which  
the bees or brood allow mites to survive or reproduce.  I remember an  
experiment in which we were looking at colonies derived from survivor  
queens.  During a period of about two months, colonies started from  
packages made out of the same large mix of bees, receiving the various  
queens, differed in as much as ten times in the number of final mites.

Anecdotal experience with random untreated splits given highly  
selected resistant bees vs. splits given unselected commercial queens  
shows that the first can end up with hardly any mites detectable,  
while the latter get to destructive mite levels by the end of the  
summer.  As some have pointed out, this is not a realistic situation  
in that not everybody has access to pure highly resistant bees and  
cannot afford to reconstitute them if queens are superseded, but the  
observation is still real.

So regardless of how mites are distributed and influxes that do not  
represent what a colony developed or did not develop, the factories  
that produce these mites are the primary source of the problem.

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