2. The living mites that drop to the floor keep falling.  This apparently is between 17% and 57%.

I am familiar with all the studies and theories. I wonder if the use of screens reduces mite infestation in the real world. If it is to be used as an IPM tool, it must have some effect on the colony that can be seen. If I have 200 hives I want to know if building all new bottoms is going to pay off in terms of reduced mite infestation. If I still have to treat with chemicals every spring and fall, what's the point of replacing all my bottom boards?

PB