Fast acting and lasting treatment with 3.5% oxalic acid dihydrate solution for brood-less colonies
One (1) part of concentrate is simply mixed with one (1) part of sugar. At a concentration of 3.5% this ready to use sugary trickling solution is well tolerated by the winter-bees and queen in the cluster.
The solution is trickled over the bees sitting between the combs. In northern Europe and at low outside temperatures the bees will remain in the hive and a dose of 5–6 ml per row for Dadant hives will be sufficient. For southern Europe and elevated temperatures an increased dose of 6–8 ml per row is required. Best results are being achieved on bees remaining inside the hive after treatment.
Oxalic acid dihydrate solution 3.5% with sugar is very well tolerated by the bees and the queen. The Varroa mite fall will peak in the first three days after the application. The sugary solution will stay active for a longer period of time since the hygroscopic sugar attracts water and keeps the oxalic acid in solution for a longer time compared to the spraying solution.
One treatment is sufficient when no closed brood cells are present. Repeated treatments on the same generation of worker bees may lead to the accumulation of sublethal effects and shorten the life span of worker bees.