For years I have consistently used slatted racks with all my hives (three
to six depending on the year) after reading that they provide additional
clustering space for the bees, control drafts, and help in overwintering in
cold climates (I'm in USDA Zone 4 in central Maine, where the snow is
usually deep and it can get pretty darned cold in the winter). I have never
had any problem with bees building comb down onto them. Now I am also using
open mesh bottoms, with a bottom board underneath, as a method of varroa
control. It occurred to me the other day that the slatted racks with their
4 plus inch wide slat at the front as a draft control, and the slats that
run perpendicularly to the frames of the hive, might be cancelling out some
of the benefits of the mesh since mites that drop could land on the slats
and climb back on the next bee rather than dropping all the way through the
mesh. I suppose I could simply make a slatted rack with the slats running
lengthwise, spaced so they are underneath the bottoms of the frames, and
get the same effect, while eliminating what amounts to the wide front slat
altogether, thus getting the additional clustering space but giving up the
supposed benefit of draft control. Any thoughts on this?