During the last few years, we have employed a few different tools in helping our bees deal with varroa mites. With screened bottom boards, we use powdered sugar dusting throughout the season. In fall, we apply Formic Acid and/or Oxalic acid to each hive to control Varroa and Tracheal mites. We have also implemented another phase of an Integrated Pest Management (IMP) scheme which involves the removal of capped drone brood. The Scientific Beekeeping Website offers a succinct overview for removal of capped drone brood as a strategy as well as using powdered sugar for Varroa control.
Sugar Dusting Method
Initially, the idea for applying Icing sugar as a mite control strategy came from Randy Oliver’s article “Powdered Sugar Dusting” in the American Bee Journal. In the past, we applied a sugar dusting to each hive on a weekly basis, and this had a positive effect on reducing mite levels. We have since discontinued to use sugar dusting as a method for varroa control, and have instead been using drone brood removal as a strategy for keeping varroa levels low during the summer.
Formic Acid Treatment
Generally, all of our hives are treated with Formic Acid in the Fall. Usually, we apply three treatments at approximately four day intervals using the Formic Acid wipes. Some hives have considerable Varroa drop from the Formic Acid, while others show very few mites on the bottom board. The Formic Acid is also applied for Tracheal Mite control. Some years, we were able to complete the three treatments with Formic Treatment. Other years, we are unable to complete all three treatments due to the cooler weather.
The last few years, we have been using Mite Away Quick Strips® (MAQS) developed by NOD Apiary Products in Ontario. We have been using the half dose treatment according to label directions, and have really liked the results and ease of use. We prefer to use this treatment because we get:
- Pre-packaged MAQS formulations: the packages come with the treatment already inside, so there is no need to be messing with measuring and dealing with liquid Formic Acid, soaking pads, and worrying about dripping on bees or the queen.
- Ability to use MAQS while honey supers are on the hives: this allows us to use the product and keep the mite levels low throughout the season, especially at the end of summer. In Manitoba, the honey flow can sometimes go to mid-September with late blooming alfalfa. If mite levels are not suppressed much earlier (i.e. mid-August), the wintering bees will have developed with a sometimes significant mite load. This leads to hive failures. MAQS allows us to treat earlier and not have to wait until honey supers are removed, as is the case with other treatments.
Oxalic Acid Treatment
Generally, all of our hives are treated with Oxalic Acid in late Fall. We apply the treatment as per the provincial guidelines for application. It is important to apply Oxalic acid when all the brood rearing has ceased, or is at a minimum amount for the year. This ensures that the Oxalic Acid Treatment is most effective, as it does not affect mites hidden in the cells of the capped brood.
Removal of Drone Brood
During the increasing portion of the bee season, all hives are given one foundation-less frame in the center of the brood chamber. When the hives are in rapid build-up mode, and when there is a honey flow, bees will quickly draw out foundation, and raise drones in the frames. Once a majority of the drone brood has been capped, the frame is removed, the capped drone brood is cut out, and bees are given another frame to raise more drone brood for removal. The brood comb with the wax can be rendered to remove the wax.
From experience we have seen that a strong hive will start to draw out and have eggs in the drone frames within two days of placement. Therefore, the drone frames should not be left in the hives for more than 24 days maximum. If drones from the drone removal frame are allowed to hatch, a mite-raising factory has been created within the hive. The principle of removing drone brood is based on the idea that mites show a preference and will more readily infest drone brood. If the drone brood is removed from the hive before the drones hatch, the mites will be trapped inside the comb and will be destroyed through rendering or other methods.
For easy identification of the drone frames, the top bars have been painted with a coloured stripe. They are instantly visible and can quickly be removed and processed.