John Keim wrote:

 Hello all:

  I understand the concept, and the reasoning, but if the screen may be
 installed year 'round, why could my bottom (assuming I am placing
colonies
 on a pallet) not consist of simply .125" X .125" hardware fabric cut
to  the
 footprint of the Hive body, then be placed under it?
 Please advise me of the  error of my logic.
Hello John and all,
Your logic is correct but a fellow beekeeper Charles Robson of
Phoenix,Arizona used a six inch square screened opening on around 3,000
of his pallets in 1979.  He said he thought problems might be had with a
larger screen by weakening the pallet.  He used the screen year around
and said he thought bees did better in transit. I can send you a close
up picture of his pallets but i imagine they are like the ones you use.
The square is dead center the bottom board.  I think screening pallets
as a IPM method for varroa control is useful.  Maybe your design will be
the design we all use.  Two things to keep in mind. At 1.5 inch the
varroa can't climb on bees and a way to keep moths from filling the area
with crap. I wonder how long or how many mites it would take to fill a
area the size of a bottom board say a inch deep with dead mites. In our
area maybe you out to go 2 inches.
Hope you found the ton of pollen supplement you asked me about. Hope
next year is best ever for your operation!
Bob