>>I think on way to verify this would be to run an experiment with solid against screen bottoms, using drone brood removal in both sets. Would the screen bottoms  be the winners?

I have heard it said that screen boards won't take care of the mites by themselves.  No doubt they will eliminate some mites but the affect will be less than desired.

My appreciation of the screened boards is for the much improved ventilation in the hot summer.  Also, a lot of hive debris falls through the screens making it easier for the bees to keep up with the housekeeping.

In the summer I have nearly full screens on the bottoms and tops of all of my colonies.  With enough supers on, I rarely see a bee beard at the entrance.

Waldemar

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