The major problem with correlating the two methods is that they measure two 
different things. The alcohol wash measures the number of mites per 100 bees 
and the natural drop measures the number of phoretic mites in the hive.

Consider two hives, A and B. A has 20,000 bees and B has 10,000 bees. Both 
hives have 1000 phoretic mites. Suppose that 1% of the mites die each day.

1) Hive A will give an alcohol wash reading of 5 mites per 100 bees. Hive B 
will give an alcohol wash reading of 10 mites per 100 bees.

2) Hive B will give a natural drop of 10 mites per day. Hive B will also 
give a natural drop of 10 mites per day.

It is clear that you can not compare one method with the other unless you 
account for the number of bees in the hive. In fact, if you use both methods 
at the same time, you can calculate the number of bees in the hive!




                                    Best regards

                                    Donald Aitken

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