OK. Oxalic acid kill the varroa. No doubt about it. But it is not the 
whole picture!

The whole picture must include damaged bees (by OA). Interaction 
between weakened (by varroa and OA) bees and virus. Remains of OA in 
the beehive which can be inhaled by beekeeper during spring 
inspection. This remains can kill the brood long after the treatment 
(next spring).

 In addition - varroa must be treated shortly after honey harvest. 
Waiting för broodless condition means waiting to long with result - 
damaged winter generation of bees.

I addition - tricklig of liquide means cooling down the beehive 
(evaporation cooling) which can start outburst of nosema or 
chalkbrood. 

All this is what I mean with the  whole picture.

\vov


 

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