>it appears that your initial average natural mite fall was about 10
>mites/day.  Your final natural fall (even with oxalic residues) at the end
>of the trial is about 7 mites per day.  So how in the world do you conclude
>that you've gotten "decent control"?

Interesting question., and very subtle one.

As you say, controls would give a comparison, assuming they lived, and a conclusion 
can only be inferred, not proven with the data at hand.  Nonetheless that is my opinion,
though less strongly held after pondering your point in light of a few additional facts I 
have been long considering, mentioned below.

I started to write a discussion, but the topic is actually very complex, and my data 
involves both alcohol wash and drops -- and I realise there is no way to transpose 
at times of transition from brood to no brood and in unknown states in between -- if
there ever is a conversion.

Let me add this to the mix.  As mentioned, bring up a point that I have pondered, 
and that is this:

If we take this chart from http://www.honeybeeworld.com/diary/incl/bj20.h5.gif
from" Survival of the mite Varroa jacobsoni Oud. (Mesostigmata: Varroidae) in 
broodless colonies of the honey bee Apis mellifera L. (Hymenoptera: Apidae) 
F. Calatayud and M. J. Verdú" -- at face value, it seems that the maximum life 
expectancy of a phoretic mite is less than 100 days in that simplified scenario.

My observations have run 60 days, with inferred broodles state for 18 days, 
so a good percentage of the original mites would have dropped as you suggest.  

In fact, if our hives could stay broodless for three months in winter, and that 
maximum lifespan applied, then our hives would be mite-free by spring.  
Somehow that never happens.

Something else:
Interestingly, in those plots, there appears to be a long tail of survivors, as if some 
mites are like our winter bees, with longer lives.  I notice that after an oxalic 
application, I see some very dark mites which are otherwise uncommon on the boards.
I wonder: Does oxalic darken lkites, or does it hit the older mites harder?  Or neither?

Your points are good, and I don't really have an answer at this point.  I am 
making some assumptions, which may or may not be valid and am anticipating 
from the trends I see and the fact that counts have not climbed at a time when
they typically do, a result which has not yet been proven.

As you say, maybe the mites would have all died off anyhow.  That would be cool.
I just do not have data to that effect.

You mention a bunch of studies.  How about sending me a few?

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