Finman,
I've read of a variety of methods for treating hives with oxalic acid. Some methods trickle a liquid solution on the frames and others use various types of vaporizers to vaporize dry oxalic acid. What method do you use? Will you describe your method, please?
George
There is heating acid = vaporazing method. It needs warm weather. Laborous, I think.
I just read fresh formula to pour solution on bees. So it is:
Hive must be without broods. If you have palm size brood area, it may contain 20% of hives mites. (But to do is better than for nothing.)
Take 7,5 gr oxalic acetic powder into 1 dl warm water.
Take 100 gr sugar and dilute it in the solution.
This 1,3 dl volume is enough for 3-5 hives, depending of the amount of bees .
Drop 4 ml solution in the middle of frames, which is full of bees from edge to edge.
Do not give for one box hive more than 40 ml, and this only for hive which is totally full of bees.
Do not give for 2 box hive more than 50 ml.
Weather can be cold, so bees are in the winter ball.
Beekeepers just chatted, what is the way, oxalic acid works. They do know but it works.
It should be a grid beneath the box, so mites cannot return to bees. In former times they used to keep greased bottom but grid seems to be better.
This method is given from professional beekeeper, one of the best in Finland Ari Seppälä.
http://www.hunaja.net/smlkoti/koulutus/opintomateriaalit/finnish%20varroa%20concept%202000%20-%202002.docSeppo Korpela is a bee rearcher in the farming university.