Varroa arrive over russian border 25 years ago to Finland.
Many medicines have used and are just now used.
Oxalic acid is now most succesfull method. Our main beekeeping consultant Ari Seppälä says that 70% of hives are handled with oxalic acid solution.
Damades for bees and quees are few with liguid. It is given at late autumn and there are no brood in hives. Vaporazind with any medicin needs quite high day temperature and early hanling. Liguid is good to give when day tempeterure is +5C or +41F. Vapour helps to thracea mites.
Handling I very cheap. I just bougt half a kilo oxalic axic crystals and price was 5 € or 6 US dollars. With that price I can handle 200-300 hives.
And again:
Oxalic liguid Metdod is very easy. It must be done during winter when bees have no brood.
If you have mites much, you can take brood off and after that you give oxalic acid.
You prepare the solution and spray it with vaccination sprayer (large needle) in the gap of frames.
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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.
(Euro coin is just 7,5 g. You can weight your coin and you can use as weight. Own balance is easy to do. Our coin weights are in internet.)
This 1,6 dl volume is enough for 3-5 hives, depending of the amount of bees .
Drop 4 ml solution in the gap 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. +5C is good weather.
DON'T GIVE TWICE HANDLING. It is harmfull.