I lose a(nother) colony, and treating with oxalic acid

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Posted by Andy Sivell | Posted in Beekeeping advice, Nucs, Varroa destructor | Posted on 23-01-2011

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Frozen nuc bee colony

Old nuc + -13C = disaster

There was no more putting it off. The snow had been and gone. The temperature had risen from “Good grief it’s cold” to “I’d probably better put a sweater on”. It was time to open up the hives and take a quick peek.

Deryck had followed up on his promise and offered me some leftover oxalic acid. I collected about 100ml in a rinsed out pint milk carton and promised to pass on whatever was left to two other novices. It felt a bit alien suiting up and lighting the smoker again, but as it was I needn’t have bothered on either count.

I started with the nuc because in my heart of hearts I knew what to expect. Sure enough, there they all were, pathetically huddled together, unmoving. Looked at at arm’s length it was like viewing a snapshot – as if someone had snapped their fingers and made the world stand still – their queen right at the center of the mob, for once really easy to spot. There was something even sadder about the single stragglers clinging frozen to the outlying frames. It’s ridiculous how attached you become to an indistinguishable group of insects, but you do.

Mouldy nuc

The inside of the nuc

I knew before I saw it where it had all gone wrong. At the height of the cold spell I’d hung a greenhouse thermometer on a post beside the nuc. Apart from reading the temperature it also records the highs and the lows. The low measured -13.2 degrees Celsius. So much for the mild micro climate. I also noticed when it was snowing that the melted water wasn’t draining from the crown board. I’d stuck a roof on top of it but it was obviously too late. All of the frames had sprouted mould, as had the walls and floor.

To be honest I didn’t really feel much like opening the main colony after that. I did though, and was immediately greeted by the gentle fizzing sound I’d heard weeks earlier when I’d bent down and placed my ear near to the entrance. When I removed the roof and crown board they too were huddled in one corner, but very much alive, though displaying a reluctance to move that put me in mind of my daughter on school days.

Following Deryck’s advice I plunged my syringe (free with every bottle of Nurofen) into the milk carton and drew 5ml of oxalic acid. I then played ‘dodge the dozy bee’ for a while as I repeatedly attempted to empty its contents down the gaps between occupied frames. In the end I used 50ml between five frames (seven gaps). I’m sure several bees got absolutely drenched, but I did my best to get it in to the spaces.

Now I need to clean out the nuc and recycle the frames. The new beekeeping year has begun.

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