>
>
> > if somebody says "I tried it and didn't notice any problems" is not the
> same as side by side comparison with a placebo.
>

Two controlled trials re the effect of OA dribble upon colony buildup that
I can think of were performed by me:
http://scientificbeekeeping.com/does-oxalic-acid-treatment-of-nucs-affect-honey-production/
and Figure 6 at
http://scientificbeekeeping.com/simple-early-treatment-of-nucs-against-varroa/
In neither case did oxalic dribble (at a brief brood break) appear to
adversely affect the buildup or honey production of nucs.  But that is not
to say that dribble *when brood is present at the time* does not have
adverse effects.  Others have demonstrated that it does.  The question may
be whether the effect upon brood is due to the sugar used in the dribble,
thus causing transfer to the brood by the bees.

We clearly could use controlled trials to see whether there are adverse
effects due to vaporization while brood is present.

> Any varroa treatment is likely to be less harmful than varroa mites
themselves,, but the notion that vaporizing acid in a hive is harmless
makes little sense to me. Just saying.

Pete's absolutely right -- I'd sacrifice some brood any day if it results
in a high-efficacy treatment against varroa.

However, I would not discount the observations of experienced beekeepers.
Last season, I kept track of two hives over the course of 9 OA
vaporizations during summer, with brood present.  To my great surprise, I
too did not notice adverse effects upon the brood.  Ditto with most
formulations of OA in glycerin.

That's certainly not to say the OA vaporization is not harmless to brood,
but I've heard from enough experienced beekeepers to reach a "current
assessment" that if OA vaporization did cause appreciative harm, that some
of us would have noticed it.

-- 
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com

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