A couple of weeks ago I removed a section of capped drone comb from the hive.

Varroa mites are known to prefer drone brood to worker brood, since it stays capped for longer and they can complete more breeding cycles within the capped cell. So I thought the mites inevitably lurking in the hive would leap eagerly into this section of early drone brood, and that I could knock down their population early in the season by removing the capped brood comb. Removal of drone brood is a recognised element of mite control, but it’s not something I usually practice.

I stored the comb in the freezer to kill the brood and avoid attack by wax moth until I had chance to examine it today. Today, I did a mite count. According to the books, you uncap the drones, pull out 100 drones that are at the pink-eyed stage (that is, relatively mature) and count the number of mites. 5 % mites (5 mites in 100 drones) is a low infestation, whereas >25% is a high infestation. So I started picking out drones:

Uncapped pink-eyed drone and white-eyed drone

In the textbook, the varroa mites were easy to see with their dark red/brown bodies contrasting against the white of the drones’ backs. In real life, I struggled to see clearly - I wondered about some dark patches and wasn’t sure if they were mites or ordinary colouring of the developing drone. It probably didn’t help that the drones (and mites) had been through a freeze/thaw cycle. It made the bodies squishy and more prone to rupture, and maybe it also dislodged mites that would otherwise be stuck to the drones.

I went through dozens seeing no mites, then on the eighty-somethingth drone, I saw this:

Yes, that’s a varroa mite on the middle drone’s legs.

It was the only mite I saw. I think.

So, a count of 1%. I have some doubts about the accuracy - maybe the freeze/thaw disrupted things, maybe I should have done the count straight after taking the comb from the hive - is it really supposed to be done on live larvae? I’m not sure whether death-by-skewer is that much worse than death-by-freezer, but it would be more unpleasant to witness and perpetrate. Anyway I don’t think I’m likely to take up drone brood uncapping as a frequent varroa monitoring practice. But still, today’s examination gives a possible indication that the mite levels in my colony are low. And if so, good!

Uncapping Drone Brood