Its not actually the winter that has been responsible, at least not on its own. Its far more the disastrous summer, and in our parts two such summers in a row. We got away with it somewhat last spring due to the lovely early weather and pollen in March, only to immediately slump into an even worse summer in 2012.
The old guys round here (I am only 58 so apparently count as a mere youth!) reckoned 2011 was the worst for 50 years (I think 1985 had slipped their memory) and 2012 was even worse.
Problem in autumn was hive condition. Not enough young bees, especially in the black bees. Those ones had slaughtered their drones in June, some of them in the first week, never raised any more, and even stimulative feeding and pollen in July failed to get the queens going properly again. Of course this did not apply to every hive, but was a strong pattern. They went into winter smallish but in the case of getting a spring like the year before a good many would have survived. Instead we get a winter that goes onand on and on, and only six days ago we had a storm of ice crystals that coated everything in the night.
MOST of the dead have just dwindled away to nothing. A little dead cluster o bigger than the palm of your hand left in the centre, which may or may not contain the queen. Plenty stores, plenty entombed pollen. Many queenless or drone layers. For the first time in many years we have a significant minority showing some signs of staining, but very few of those are severely fouled.
A FEW showing the 'exploded cluster' symptom, where all the bees are dead but at the extremities of the brood box.
Black bee losses by far the highest.
Non black bees the most likely to be showing some staining.
In both cases poly hives far far lower incidence of the symptoms. Attributing this to the boxes being warmer in winter is, I feel, erroneous. They had a better hive environment in late summer and were far more likely to raise another generation of brood prior to going into winter (we could see this difference in Spetember when stripping off the heather honey) and thus simply had enough young bees to withstand the winter. Very few signs of varroa, and few varroa noted on the floors of the dead outs.
So, not the winter that killed them per se, it was lst summer, exacerbated by the length of winter. Until the cluster gets very tiny the cold itself will not kill them. Already have all the northern dead outs fumigated with acetic acid as a precaution againt nosema spread.
Even on this forum this outcome was predicted by me way back at the tail of last summer. The weather alone from late May right through was enough to give rise to this effect. 1985 was much the same, and winter carnage followed, perhaps even worse than this. No need to introduce new variables to explain it. All the old killers that gave rise to losses in the past are still out there. Add varroa pressure on top and we have major issues to face, and a double whammy of horrible summer and bad mating, run on into a very long winter with the worst weather at the most sensitive time, and a poor outcome in inevitable.
