Monitoring for Varroa

A few beekeeping friends and I took a course several months ago and there was one thing that Mike (the host) mentioned that stuck with me: you should monitor your varroa mite loads by doing regular sugar rolls.
Now if you’ve been reading my blog for a while, you know I do sugar rolls and I treated my hives using formic acid which is considered a “soft-chemical.”

He noted that most beekeepers who treat their hives don’t monitor the problem to get an idea of how bad it really is, which you would only know by doing regular checks. For example, what if your hive had 15 mites per 300 bees? You would likely decide to treat. But what if it has been 15 mites per 300 bees for the past 3 months? Should you treat?
That’s up to the beekeeper, but doing regular sugar rolls will help to monitor the health of the colonies and show the effectiveness of other mite control methods (drone trapping, sugar dusting, brood breaks). So I plan to start sugar rolls every week for 4 weeks. I hope I can keep up with it and the weather cooperates.

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3 comments

    • I hope SuburbanRancher pardons me sticking my oar in but the procedure we were shown is from:

      http://www.michiganbees.org/2010/sugar-dusting-your-vorroa-mites/

      There are (or used to be) many versions bandied about, some of which lacked critical details. It is critical to get the bees from the brood area. Not so critical to avoid capturing the queen if one is not a good queen spotter; she ought to survive the indignity. The sugar is powdered rather than granular sugar, although I could not find where the article points this out. We recall some controversy about cornstarch in the sugar. And #8 hardware cloth has a square mesh of 1/8″ between wires, coarse enough to pass varroa and sugar but fine enough to contain bees.

    • Not at all prospect, I couldn’t reply right away due to work. But yes the procedure calls for using bees (preferably from the brood frames), they are shaken into a jar (I shook them onto a bent piece of flashing to be able to pour the bees into the jar, which was much easier), cover them with a mesh screen, you put a generous amount of powdered sugar through the screen and shake the bees until they’re coated with the sugar. Let them sit for a minute or 2 and then shake the jar over a white piece of material; I set a pie plate on top of white paper and put water in the plate after shaking the mites out, this makes the sugar dissolve and the mites very easy to see and count. The powdered sugar dislodges the phoretic mites from the bees, it’s this number of mites that helps to determine whether you should treat or not (this can vary on your location). The link in prospect’s reply is perfect. I used the reference from Marla Spivak, University of Minnesota which is viewable via a Google search for “powdered sugar roll varroa” and it’s the “beelab.umn.edu” address.
      You’ll find a few references to adjusting the number of mites based on whether the sample is from brood frames or not. I believe the test was designed using brood frames, so that’s what I stick with. There is also variable information regarding the number of bees to be used for a sample, my reference says 200-400 bees, you can use finger width to estimate the number which is very variable, or a measuring cup to keep it consistent.

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