Winter Varroa Treatment

The last main job of the year is the winter varroa treatment. Hopefully the partial removal of the mites strengthens the colony to make it more likely they will survive the winter.

Unlike the treatment in Autumn, this involves using Oxalic acid which is a particularly nasty substance that's highly corrosive and should not be handled or inhaled. You can buy it ready made in a 5% solution or tubs of crystals and you make it up yourself. A 500ml bottle and syringe that will do 10 hives costs £10. It has a very short shelf life.

It doesn't completely get rid of all the mites but can kill up to 90% of them. However it also kill the bee brood so it can only be administered in winter when the queen has stopped laying.

The usual way of administering OA is by dripping it into each seam of bees using a syringe at 5ml per per seam; a seam is the gap between the wooden frames. The OA needs to be warmed so as not to shock the bees and if possible it should be done on a warmish day to prevent too much heat loss when the hive is opened.

After using the syringe method for some years I bought an automatic syringe that you calibrate to the dose you want and once the dose has been applied, it refills itself automatically. This means the process is much quicker and there is less disturbance to the bees.

Last year I was talking to a very experienced bee keeper with ~130 colonies and he said the previous winter he had used something called a vapouriser for the first time. He had borrowed it but as it was so successful he intended buying one himself.
'If its good enough for Ken, its good enough for me', I thought and decided to get one myself.
Bee keeping equipment in this country is stupidly expensive but I managed to get one from Germany at two-thirds of the cost here. The instructions were in German but there were numerous Internet articles and YouTube videos on how to use it.

It works by putting 1gm of oxalic crystals in the round bowl at the top of the vapouriser which is then inserted in the front entrance of the hive. To keep as much vapour in the hive as possible a blanket is put around the entrance and also at the back of the hive where the varroa sheet goes.The crocodile clips are then attached to a 12v car battery that heats up the element that vapourises the crystals which then coats the bees.