I reviewed the oxalic vaporization process with  a PhD chemist I know 
well as a friend. I posted my discussion with him here last fall and it 
should be in the archives. 

Long story short a direct inhaltion is quite serious and could  have 
permanent heatlh effects. He suggested I wear a NIOSH approved 
respirator which I do while working with the vaporizer. . 

What is more appealing about vaporization then the liquid trickle 
method is if you have hundreds of hives and want to wait for the 
broodless period you do not need to open the hives up in cold 
weather. 

The way I see it is if I want to use oxalic I need to get my hives into 
November and the broodless period.  We are using apiguard this year 
(once instead of 2 treatments) to treat only hives with higher mite 
levels. The rest wait til November when all hives are treated with oxalic 
vaporization.. 

Its a bit risky in the sense you must rely on mite levels to decide what 
to treat early and what can wait. Weather here in Mn during November 
can historically vary all over the board. Can't see counting on being 
able to open a hive in November to trickle so I go with vaporization.  

If the weather turns real cold I can still wait for a break in the weather 
(mid 30's) and treat any time in early winter. We wrap bees here for 
winter too and thats another issue that makes late broodless 
treatment a problem and the trickle method impractical. I'd like to wrap 
once feeding is done in mid October and come back later in 
November for oxalic. 

So here in Minnesota vaporization makes sense, is cheap and in my 
experience works very well.

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