In my last two blogs (What Is It and Mixing it for Hive Use) I discussed the benefits of using oxalic acid as a way to manage the number of Varroa mites in our beehives and how to effectively mix it with sugar syrup for application. Now I will describe in detail how to safely apply it using the dribble method. You might read about other methods for applying oxalic acid as a mite treatment, like sublimation, but I find that the dribble method is easier (requires fewer materials and less of an investment) and is also safer to the beekeeper (less risk of inhaling and causing respiratory damage). Safety comes first here. It is best to wear gloves, goggles, and a long sleeve shirt when working with oxalic acid to avoid irritation to the skin or eyes.
The best time to apply oxalic acid is when there is little to no brood, making winter a prime time (late November to early February). However, it is cold in winter and opening a hive during freezing temperatures isn’t ideal. Therefore, keep your eyes on the weather! Watch for a day where it is roughly 55 degrees. Opening a hive for a brief moment during a day like this limits the risk of exposing them to cold temperatures, but it is still cool enough that the bees are clustered together to keep warm.
- Next, you’ll want to make sure you have all the needed supplies so you can work relatively quick. You can buy a full kit through Brushy Mountain Bee Farm.
- Safety gear noted above (gloves, long sleeve shirt, and glasses/goggles).
- A syringe that allows you to dribble a measured 5 mL of the mixed oxalic solution at a time. Again, a basic syringe comes in the Brushy Mountain kit, but I purchased one that has a pistol grip which allows me to pull the trigger-like handle and release exactly 5 mL with each pull. It’s very easy! A picture is below.
- A container or jar that has a wide enough mouth to allow you to suction the solution into your syringe for application. A mason jar or old sour cream container will do just fine!
- A buddy! I find it is helpful to have one person crack open the hive while the other person applies the solution. It seems to go quicker with less risk of dropping something. (Spouses, a curious neighbor, or someone you’re dating and trying to impress work really well here).
Now for the application technique! The goal is to dribble 5 mL of the oxalic acid solution between each of the 10 frames (50 mL total). You want the solution to come directly in contact with the bee’s bodies since oxalic acid works by making contact with the mites on the bee’s little bodies. Try to drip it between the frames rather than on the top bars. Their movement will mix the solution around the hive. You will notice in early winter that your bees’ cluster is likely toward the bottom of your stacked hive boxes, but in late winter they have eaten through the honey and moved upward. With this in mind, you need to know where your bees’ cluster is located so that you can ensure that you dribble the solution on the majority of the bees and not only on the bottom of their cluster. The best way to know is to crack it open on that 55 degree day and assess before applying.
I helped the Boise State bee keeping students with their application. We found a 55 degree day in December and jumped at the chance to kill some mites. We noticed on this hive that the vast majority of the cluster was in the bottom box. Therefore, the students dribbled 5 mL between each of the frames on the bottom box. Two students used a hive took to crack and lift the top box, while a third dribbled the solution between the frames. The bees weren’t too impressed with us cracking open their home, so we worked quickly and moved onto the next hive.
There will inevitably be another 55-degree day in January and February for you to do the same with your hive. Although you might find that the cluster has worked its way up through the honey they stored. In this case, you would want to just remove the top cover and dribble the solution onto the top of the highest box. Keep in mind that one treatment per winter is good enough. Over treating is unnecessary and can put your bees at risk.
I have dedicated a lot of blog space to the issue of Varroa mites. I do so because I want to convey the importance of managing their numbers in our hives. A strong beehive has few mites, and the good news is there are ways to keep their numbers low. It isn’t always easy – it takes careful consideration of the beekeeper to count the mites, determine the method for reducing them, and doing so effectively. Remember to always be a beekeeper, not merely a bee-haver.
Keep your bees buzzin’ y’all!