My memory was refreshed by a friend who reminded me that the OA foggers
used in Cal, Canada and Europe are just a stepped up  variant of the direct
sublimation fogger, the wand, that I use.There is no OA solution, but
direct heating of the OA and the vapor is forced into the hive by blowers.

So Dick's trials of the blower using water and having no effect makes
sense. In essence, the fogger is fogging not OA but alcohol or water. You
are not blowing vaporized OA but steam and alcohol. With the boiling point
of each being much lower than OA, the OA does not have a chance to do much
of anything.

I have long thought, but cannot prove, that there is more to direct OA
vaporization than just the deposit of OA crystals in the hive. My guess is
that Formic Acid vapor plays a role, but I am hard pressed to prove that.

But it is not too hard to see why direct OA heating to vapor and condensing
in the hive would be different than OA in solution heating to vapor and
condensing in the hive. The first would result in OA itself condensing out
and the result would be more powder than the crystals you started with.
While the solution would result in the condensing of the carrier
(water/FGMO/alcohol/whatever) and then the recrystallization of the OA, not
in a powder but more like the crystals you started with or larger.

If the mechanism is through the foot pads of the mites, it seems obvious
that fine powder would be more effective than crystals.But you could still
have some mite control, especially when you look and see how much OA is
actually being put into the hives with the unregulated dosage.Plus, I would
think that powdered OA would present less danger to the bees than larger
crystals.The OA dribble method comes to mind.

But the worst is the very unregulated dosage. Three "sprits" just does not
work with me. If you watch the videos it is obvious that even the "sprits"
are variable in the vapor they produce. Many seem more droplets than vapor,
so the applicator hits the button a few more times to get the right amount
of vapor.OAV is very forgiving in the range of dosage before problems
ensue, but there is no regulation of dosage with the fogger. That is very
apparent in the comment of the user who lent his fogger to a friend who
then lost all his hives. I have yet to hear from anyone who has used the
wand who has lost bees. I have carpets in front of my hives so I can see
what they throw out and I never see any increase in the refuse after an OAV
wand treatment while the carpet is littered with dead bees after MAQS.

Anyway- thanks Dick for doing the heavy lifting and I see no good reason to
even trial the fogger next year when I have my new hips.

Bill Truesdell
Bath, Maine

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