Oxalic acid is an organic compound with the formula H2C2O4. It is a colorless crystalline solid that dissolves in water to give colorless solutions. Oral consumption of oxalic acid in excess or prolonged skin contact can be dangerous. Oxalic acid has toxic effects through contact and if ingested. It has been reported that the lethal oral dose is 15 to 30 grams.
How to use the oxalic acid in varroa treatment:
100gr oxal acid
1,5 l water
1,5 kg sugar
With this quantities you have enough to treat roughly 60-70 colonies. It is the best to treat the bees within 7 days of preparation. 25ml-35ml is enough for one colony. Approximately 5ml for one gap between honeycombs where are the bees positioned. It is not recommended to prepare less of this quantities: 0,6 liter of water 0,6 kg of sugar 37,5 gr of oxalic acid Just from simple reason it is very easy to make mistakes for smaller quantities. In that case it could be very dangerous for bees or with no treatment for varroa.
Application of oxalic acid is possible dropwise fluid in the gaps between honeycomb directly to bees. You can use medical injection.
WARNING: The treatment is necessarily done with the use of protective gloves, protective eyewear, masks and appropriate protective work clothes. (See manufacturer’s instructions) Nearby should be prepared supplies of clean water for possible washing. Use only once a year when no brood in colony. It is recommended to use it only once per one bee generation. Usually beekeepers treat bees in late November or early december with oxalic acid.
CAUTION: There are several evidence that colony shouln’t enter early spring with more of 50 varroa mites. Also there are evidence that treatment of oxalic acid has 90% efficiency. It is the best to check within 7-14 days hive bottoms and if you find more than 450 of dead varroa mites after treatment it is very simple to conclude there is more than 50 left, to calculate how many, to realize the colony have a problem and you have to treat with something else too to save the colony.