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During September we started our treatments against Varroa mites. The first stage of this treatments was carried out by using Formic Acid (it was applied on paper napkins). The napkins were impregnated with 2.7 ml of Formic Acid (60%) for every frame. These quantities were used for swarms and colonies on 4 to 10 Dadant frames and the napkins were placed inside plastic bags to prevent the acid from evaporate. On every bag we marked the number of frames in accordance with the quantity of the acid being used. Then, upon checking the hive, we chose an appropriate bag for the number of frames of that particular colony and made a few cuts in the bag to allow the acid to disperse. The Formic Acid was diluted from 85% to 60% by adding 1 Liter of acid to 495 ml of water.
Please note the order of the above operation as it is very important; if we add water to the acid there is a chemical reaction that releases heat and it can be very dangerous. Also, when working with Formic Acid precaution measures are absolutely mandatory (mask and gloves) and all of the operations must be carried out in open spaces. The treatment duration is 7 to 10 days and can be repeated one or two times. We left the napkins for 7 days and after a few days we followed up with an Amitraz treatment (as we’ll describe it later in this article).
Why Formic Acid?
Pros: it is efficient against Varroa mites even in the case of capped brood, Varroa doesn’t form resistance to it, it doesn’t leave any residues in honey of frames, it works even against Acarapis Woodi.
Cons: its efficiency varies greatly by depending on multiple factors like temperature (must be between 12 and 25 degrees Celsius), the method of applying the acid (paper napkins, cloth, vaporizer etc).
As we previously said, we chose the paper napkin for its large surface that allows an effective dispersion of the acid and by placing them inside plastic bags (that were only cut in a few areas) the bees won’t be directly exposed to the acid. It’s a well known fact that the queen can even die if she comes in direct contact with the formic acid. Even so, by carefully gathering feedback from many beekeepers, we do believe that using a cloth napkin is a better approach; they can be placed directly on the frames and with a syringe we simply apply the quantity of acid according to the size of the colony. The surface is still large enough and the whole operation is less time consuming than in the case of the paper napkins placed inside plastic bags.
In the second stage of the treatment we placed sticks made of fir tree inside the hives after they were impregnated with Amitraz (we used Taktic) and sunflower oil. The solution contained 250 ml of Taktic and 1.8 liters of sunflower oil. The sticks were 20 centimeters long, 2 centimeters wide 2 millimeters thick. They were placed in the aforementioned solution for 24 hours, then left to dry for a few hours before being placed inside the hives. Until the passed year we used a similar method, the difference being in the dimension of the sticks and the fact that they were placed on the bottom of the hive. Our current method was selected after testing both of them with excellent (and identical) results. We prefer the method described above (the sticks are placed between the frames) as it is more practical and requires less time.
The final two treatments will be carried out in the same manner, by placing Amitraz sticks inside the hives, with the specification that the last treatment will be made when there isn’t any more brood in the colonies. Below you’ll find a video that we recorded in September that also depicts the methods from this article.