Varroa

From what I've read, the 'Varroa Destructor' mite was introduced to the UK many years ago from import of foreign bees - probably from Asia. - Even from early 'managed' beekeeping, bees from abroad have been imported around the world, and as with other animal introductions, it causes unforeseen consequences. - The 'native' bees in the UK have little natural resistance to the varroa mite, and it is therefore a serious problem for all UK based beekeepers.

The varroa mite is itself implicated in 'colony collapse disorder', and can carry diseases such as 'deformed wing virus' which can also reduce the efficiency of the colony as an organism.

Varroa appears to be almost like a 'tick' on a person or a dog, but with much larger relative size to it's host, and consequently more damaging to the host.  It breeds quickly, and appears to be ubiquitous throughout the UK.  Anyone becoming a beekeeper needs to be aware of the mite, and methods for managing it.  No management methods kill 100% of the mites, and they will always re-breed and if left will ultimately reach a level which will overwhelm the hive. - It's therefore important to maintain as low a level of mites as possible.

A few days ago I put the 'varroa floor' under the mesh floor of the hive to measure the rate of mites falling from the hive. - This gives an indication of the total mite infestation of the hive, and whether to actively treat at that point or not. - I counted about 40 mites over 4 day period so around 10 mites per day. - This might be an underestimation because I didn't use anything sticky on the floor - I think I should maybe coat it with olive oil or something so the live and dead mites stick to the board.  At this level, recommendation seem to be that treatment is not immediately required, but it's something I'm thinking about as we approach cooler weather and we start to think about the bees going into winter.

These brown blobs are varroa mites.  They are roughly 1 x 1.5mm, so pretty small, and tricky to photograph.

There are various lines of defence / treatment to reduce the numbers of mites in the colony and I will use a number of these to try to control it.

1. - Mesh floor. - This is simple - the mites which fall off the bees pass through the floor and can't get back onto another bee - easy & a good reason for using a mesh floor.

2. - Icing sugar (powdered sugar).  It is thought that dusting the bees with icing sugar causes more problems for the mites.  It also encourages the bees to 'groom' each other and remove the sugar, knocking off more mites. - This is clearly a relatively less risky treatment as sugar is a relatively innocuous substance to introduce to the hive in the grand scheme of things. - I will dust with sugar at next inspection.

3. - Sacrificial brood. - The varroa mite favours drone brood.  These cells are larger than the worker brood, and drones take the longest to incubate giving the mites more time to mature in the cells with the bees. - During a couple of hive inspections with the local association, we've removed some immature drone from their capped cells, and these can have several mites already visible and grown on the bees. - Not a good start!  - However supposedly you can encourage the bees to make drone cells by putting a shorter super frame into the deep box - The bees will build natural comb onto the bottom of this frame to fill the space, and then you can 'sacrifice / destroy' this comb and the mites therein. - This is something I will try next year.

4. - I'm not hugely in favour of using chemicals in the hive, but since I have no expectation of honey etc until next year I will probably try a 'Thymol' based treatment - apiguard which at least isn't an 'engineered' chemical. - Since I only have one hive, I'm keen to give it the best chance I can of surviving the winter in a strong state.  I've ordered some 'apiguard' as it needs to be used whilst weather is still relatively warm.