At the recent ABA convention, Cor De Wit described his experimental set-up for using oxalic acid vaporization to control varroa. I was so impressed, that I asked him for his slides and he obliged. In fact, he drove to Edmonton, had them put onto a CD and sent them to me -- and he won't let me pay him for the effort.
At first, Cor tried the VARROX oxalic
evaporator as designed and recommended, but encountered some problems:
Treatment took too much time per hive for commercial bee operations with hundreds or thousands of hives
Fumes were escaping out of the entrance and cracks in the hive, lowering efficacy and presenting a hazard
The low clearance of entrances in North American hives resulted in poor circulation of fumes in the hive, and possible fire hazard.
Click on any thumbnail photo for a full-size view.
Here's the VARROX Verdampfer, used as designed. There is an obvious clearance problem.
|Cor decided to use the best
features of the device, but to improve on the method of use to increase
convenience and efficacy, and to reduce hazards to the operator. He
built a cart with automotive batteries and a fan, and developed a
small sheet metal enclosure for the VARROX verdampfer.
The enclosure has an inlet for the fan, a spout to fit easily into the hive entrance through the small hole in the reducer, and a filler funnel, into which the oxalic can be dropped onto the hotplate of the VARROX verdamfer. A cork plugs the filler hole to prevent fumes escaping there when the fan is activated. The boxes have legs and a handle to make it easy to swing one into place in front of each and have it stay it there during two minutes of the treatment.
A timer on the cart turns the fan off after two minutes. I think it controls the VARROX evaporator as well, but I'll have to ask and learn more about the details.
Here are some salient facts:
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Using Formic & Oxalic Acids for treatment of Varroa & Tracheal Mites
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