Allen is right when he says that Europeans have more experience with oxalic acid. We in Finland are novices as the use of oxalic was started about 10 years ago. Russians and Estonians have been evaporation method for about 20 years.

I have heard lots of talks about oxalic breaking to formic. I would say that one does not have to bother much about it, as formic also kills varroa. But  I would recommend to evaporate  oxalic with temperatures below  about + 180 - 200 C . I have met beekeepers who have home made evaporators ( 1 feet of steel pipe with tight lid, propane torch, + air mattress pump to put the gas going)  One fellow told that for many years he did not have good results. Then he heard about oxalic breaking and invested 10 euro for thermometer to be able to see the actual temperature in tube. He tries to keep it between + 100 and +150 C. He said that the efficacy increased a lot.

At this point I must say that I recommend oxalic in water/ sugar solution because it is safer for beekeepers. Beekeepers have taken this advice. Less than 5 % of beekeepers who use oxalic evaporate it here.

Allen
>I do wonder, though, since I know
>some of them are using triple the dose that I would. Maybe they need to.

Most likely they don't need to. As with fluvalinate and antibiotics we always have beekeepers who think that doubling or tripling the recommended amounts give better results.

I bet they drive always 150 mph as that way they don't have to be so long on road, less chance for an accident ..


Ari Seppälä
Finland

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