1992 a special year for us and the year Varroa mites were first discovered in UK.
Varroa mites were a known parasite of the Asian bee but they are thought to have crossed over to the European bee in the 1960s. In 1992 they were first discovered in the UK and now they are everywhere.
With average temperatures falling, this is the time of year when Queen B and Queen G are starting to lay fewer eggs but those that they do lay now will hatch to become the bees that will live throughout the Winter. The bees that have been working hard all year gradually die off at the end of their natural lives so the number of bees in a large colony reduces from perhaps 70,000 to 10,000.
It is recommended that we treat the colonies to reduce the number of Varroa mites now so that the over-wintering bees start out with as few pests as possible, giving them slightly less to do as they battle to survive to next Spring. Varroa mites stick on to bees sucking “blood” (actually hemolymph) and weakening them. The open wounds that are left leave the bees more prone to infection. Varroa mites also hop on and off bees so they can transmit disease from one colony to another. They prefer to lay eggs in drone cells but in the Autumn, all the drones are expelled so Varroa mites switch to ordinary worker bees.
Before we start the treatment process, we have to check the number of Varroa mites in the colonies already. Luckily, I picked up tips at the last beekeeping theory class in early August, so a couple of weeks ago we smeared Vaseline round the edge of the boards that slide in under the mesh floors of the hives and sprayed the boards inside the Vaseline liberally with cooking spray – yes the oil you spray on your frying pan. After a week this was the result for Queen B and her colony:
You can see the stripes of debris falling from the frames. At the front of the hive (top of the picture) there is an area of wax bits and pollen. The bright orange is Dahlia and the less bright orange is Michaelmas Daisy or Aster pollen. The pale yellow is probably Himalayan Balsam.
At the back of the hive is what we’re interested in. Those larger round reddish brown discs are dead Varroa mites. We counted about 16 and did the maths. These bees don’t have a bad infestation but this will give us something to compare with the results after Varroa treatment.
As you will have come to expect, the G Bees are different. On the G Bees’ floor, the stripes aren’t noticeable. I suspect this is because there are so many bees in the colony and so much debris that it spreads out. We might have got stripes if we’d left the floor in for a shorter period, say 24 hours instead of a week. Or, perhaps some creatures breached the Vaseline barrier and ran around on the board spreading the debris about.
It ‘s all the more surprising then, given how large the G Bees' colony is, that there aren’t any visible signs of a Varroa! I wonder whether it’s because the board is made of wood rather than metal. Perhaps the Vaseline did soak in more and didn’t prevent earwigs and other bugs from getting on the board and eating whatever they wanted. There’s an even spread of wax bits but not so much pollen either. The pollen we can see is yellow possibly from squashes and almost white. It’s a bit late for sweet corn but there is a field within eyesight and sweet corn pollen is apparently white.
Or, perhaps this colony genuinely doesn’t have Varroa. Any thoughts anyone?
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