> > Moreover, most experts agree that formic alone will not always control
> > varroa sufficiently that Apistan will never be needed.  Usually there
> > is a recommendation to monitor mite levels and rotate treatments where
> > varroa is a problem.
 
> It is the later point that tempts me to consider them, there are times
> when manipulation is unwise or when the mites are in the brood and we're
> to close to a flow to wait, a volatile like formic might be quite useful
> and give us another bite.
 
Yup, exactly.  But IMO, *pads* are the answer.  They give a series of
quick 'hits'.  Several well timed hits knock back the mites without
leaving the bees in a corrosive environment over time.
 
> each unit must be placed fairly close to the brood,
 
So do the pads, but you need not pull frames, etc.  Pads are much less
invasive and labour intensive.
 
> > I understand that it must be in a half-frame in place of a comb.
> > Does this not have the advantage of making the evaporation more stable?
 
I don't see how, but maybe.  I think the atmosphere at the top of a hive
is much more likely to be moderated than that in lower areas.
 
> One of the problems of pads or plates above or below the brood nest in
> British weather is the variation in the rate of evaporation and the need
> to monitor. By putting it into the brood nest the bees will maintain a
> constant environment for us.
 
Pads do go on top of the upper brood box frames, either in the centre, or
further out, sepending on your appraisal of the situation.  (Maybe someone
like Kerry can help me here).
 
The Nassenheider Evaporator is to be placed behind the next comb to the
brood according to their literature.  This may place it out of the
cluster or below the cluster.  It depends a lot on the hive config, I
think.
 
> > This means having a big gap in the frames where the thing sits.
> > This is likely to cause poor wintering (colony death) here in Alberta.
 
> I think this would be true for us here to, and I accept your point
> about handling the acid. Its useful too that you point out that
> Nassenheider's are probably an additional expense. I can't see economic
> grounds for using them at all. ('Cept if you count the bees that are
> lost maybe.)
 
> Dave Black, Guildford, GU1 4RN.  UK.
 
Don't get me wrong. I think the Nassenheider Evaporators may have their
place.  It is just that it is not in commercial service.  My article was
to a post that made them sound (to me at least) like a proposed panacea
for mite control and proposed commercial beekeepers use them.  It is from
that perspective that I wrote.
 
I believe the Nassenheider Evaporators, and the Popodi device for that
matter, are fine for hobbyists and others who aren't paying labour, don't
have to haul free acid in & on crowded trucks, and don't care if they get
a crop.
 
The Nassenheider Evaporator literature seems to me to be a bit optimistic
and neglects that controlling these mites is sometimes easy, and at other
times difficult.
 
Apistan is still the standard against which we measure success and is
often still necessary in rotation with formic, since it formic has had
some notable failures, and is also of limited usefulness against high
varroa infestations.
 
The Nassenheider Evaporator just seems to me to be a difficult, fiddly and
expensive way to do a simple job.
 
As usual, I'd love to be proven wrong.
 
 
Allen Dick                                  VE6CFK
Rural Route One, Swalwell, Alberta  Canada T0M 1Y0
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