Peter Borst wrote:

> I am familiar with all the studies and theories. I wonder if the use of screens reduces mite infestation in the real world. If I still have to treat with chemicals every spring and fall, what's the point of replacing all my bottom boards?

They do slow mite infestation, but varroa will still win if not treated.
But, when used in conjunction with treatments other than strips, that
cause mite fall (such as wintergreen patties) they keep the fallen mites
out of the hive so can keep the infestation under some control. You will
even have mite drop when you smoke the hive. So you may be able to
reduce treatments with strips.

They also have other benefits, especially in promoting ventilation in
all seasons. Beekeepers in Denmark used them just for ventilation when
moving hives for pollination. So I can see no drawbacks from using them
except slower spring buildup.

I would be interested in what the dynamics are on mites over wintering
in open mesh floor hives. It would seem that there should be a fair
number that succumb to the cold and fall, adding to the effectiveness of
OMF.

Bill Truesdell
Bath, ME