From: "P-O Gustafsson" <[log in to unmask]>


> > Ari Seppälä <[log in to unmask]>
>
>  > Vaporizing oxalic acid takes 15 times longer than drizzling. Drizzling
takes
>  > about 1 - 2 minutes / hive. About the same time as placing strips.
Drizzling
>  > is also much safer.  Oxalic acid vapor  is not nice when you inhale it.
>  >
> After testing both methods I must agree with Ari, there is no need to make
> things more complicated and expensive than necessary. From my experience
it
> takes no more than 30 sec to apply a sugar-water-oxalic mixture to a 2
boxes
> hive in autumn. I found no difference in efficiency between the methods.
>
> We beekeepers often believe that a method is better because it's
complicated and
> / or expensive. I have personally found it's usually the other way around,
> simpler is better.


Although I have not used a trickle system, my observations don't tally with
either Ari or P-O Gustafsson.  I bought a Heilyser vaporizer late last fall
(from Canada), and found it cheap (around $65 U.S.), fast (about 3 minutes
per hive - no need to open the hive), and convenient (can be used once/week
in any temperatures above freezing, making it very flexible for early/late
winter broodless treatments which provide the highest efficacy).  Maybe
others are faster at opening a hive than I, but I don't see myself doing any
sort of invasive procedure like an acid trickle in much less than 5-7
minutes per hive for a two story hive.

Some key differences between the Heilyser and the European designs I have
seen are:

1) Heilyser uses a simple propane torch for heat (fast) as opposed to
electric coils
(slow).  This also eliminates heat directly in the hive, which I've read is
a problem with foam hives.

2)  Very simple design that's flexible for different hive openings etc.  The
vapor passes through tubing, driven by user supplied air pump.  the unit
sets on a stake, and the user passes a torch under the heat tube and pumps
air until the vapor is delivered.

Some suggestions/observations that I would make for using the torch type
vaporizers are:

1)  In cold weather, use pipe insulation on the tubing carrying the vapor.
The first time I used mine in cold weather, I noticed a fair amount of
condensate/precipitate forming on the cold tubing, indicating reduction of
delivered dose.  Also try to keep the delivery hose as short as is
convenient.

2)  I would (will) build a small carrying unit which houses the entire
apparatus, and fixes the torch below the heating tube.  This would make it
possible to use it in a more hands-off fashion, or run multiple vaporizers,
and make it easier to transport.

3)  I have been using a hand pump, but I think a foot pump would probably be
better.

4)  Make foam entrance blocks for all openings.  Make multiple sets so that
you can pull the tube from the entrance block to move to the next hive while
leaving the previous closed for a few minutes.

5)  In warmer weather, try to treat early in the day, before flight, and
while it's still cool.  The need for a respirator/filter would be an obvious
issue on a hot day, as would the need to stop up the hive for a few minutes
(not to mention the absence of foragers and their phoretic mites during the
day).

I have only dabbled with my vaporizer so far (I will be keeping records
soon), but the claims seem real.  Of the two hives I treated in March (1st
year hives last year, with no other treatment of any kind) one is only now
starting to show mite drops (around 1-3/day).  The other hive was a dead-out
from the brutal winter we had.

Regards,

Todd

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