Ruary states
 
>Use of the BBC /MAFF calculator shows that a NATURAL mite drop of 200 per<
>day in March is required before treatment would be needed in September. If<
>testing with Bayvarrol or Apistan is used the mite drop could well be some<
>360 times larger assuming a 90% efficiency.<
 
 
I believe he is failing to use the Conversion Chart at the rear of the
BBKA/MAFF calculator which states for the month of March;
 
Daily mite fall X 100 = Estimated number of mites in colony. (Rough
estimation)
 
So Natural Mite Mortality of 200 per day = 20,000 mites in the colony, a
severely infested colony probably past the point where any treatment will
prove useful, and way off the edge of the calculator which only rises to
5,000.
 
Ken Hoare