> One last rant and I will sit down and shut-up, I promise.

I have very much appreciated your contributions.  Don't stop. I am sure
your observations will cause others to be less inclined to just assume
that because they treated that they can sleep for a while.

> Any one that has followed this thread from the start knows that I
> started by stating my alarm at finding lots of surviving mites when I
> pulled the strips.... My questions were always about the claim of
> killing mites in capped cells and not harming the pupae. Are there
> any studies variying those claims. Those questions remain
> unanswered.

Actually, they have been answered, but the answer is not as cut and
dried as we would like or the one we want to hear.

Yes, that claim is true for some lucky cells, but not others. In those
not in the 'zone', the mites and the immature bees will be damaged or
killed and in other cells neither will suffer much harm.  It is a matter
of luck and location.

The formic concentration with any application method will vary with
distance from the strips, temperatures and numerous other factors.  That
concentration will vary from place to place in the hive and from
harmless to lethal for mites, and for bees.

The concentration and exposure time required to kill the average bee,
larva, pupa, mite or immature mite will be all different.

Moreover the contents of each cell will vary in how well they are
protected by clustering bees, varying capping density, air currents,
etc. etc.

Inasmuch as there is no practical way to control the formic vapour
concentration at any specific point in the hive since the brood and bees
are at varying distances from the strips or pads and since the ambient
temperature or air circulation in hives can vary in an unpredictable
fashion, we can deduce that in some areas the concentration will be
optimal and in others either higher or lower than desired or that the
duration of that concentration may also be variable.

Where that ideal concentration exists for the required period of time,
without exceeding a lethal dose or duration (for bees and immature
bees), but exceeds the level required to kill varroa females and males
(males are smaller) males will be killed.  That has never been a secret
and we have talked about it here for at least a decade.

The problem, as Bob pointed out repeatedly is that the way to know you
got a mite kill is to see that you also have some 'collateral damage' in
the form of some killed brood.

So, yes, that phenomenon has been observed and documented, but how
useful or reliable it is in practice can be questioned -- as you have seen.

Almost all fumigation methods suffer from these problems of uncontrolled
release and concentrations.  That is why the 'cattle oiler' methods work
so much better and are much less subject to the effects of weather
colony size, hive geometry, etc.

These latter methods rely on bees rubbing on the source strip and
distributing minute amounts as the brush against and groom one another.

I wonder if Mitegone and the Amrine board may manage to get more even
and predictable fumigation.  The Apinovar method also seems to be quite
consistent.

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