Hi All,
I've used screen bottom boards now for the full year in south eastern
Ontario.  First, the bees do not defecate in the hive.  They need good
weather for cleansing flights.  Assuming good health and all.  My boards are
not open to the earth but have a debris board under it.  I find this useful
to monitor hive activity through the seasons.  I had an extremely heavy
varroa infestation last summer prior to building the boards.  After
installing and putting in Apistan the mite drop in 24 and 48 hours was to
heavy to count.  Through out this year my mite fall has been 0 to 5 mites in
24 and 48 hours. I am removing the last suppers tomorrow so will install the
Apistan.  This is going to be interesting to see if the small mite drop
through out the summer will correlate with the Apistan drop.

Kent Stienburg