Regarding wintering, a pretty clear picture emerges: historically beekeepers assumed that at least a third of their colonies would not over winter, because they were subpar. Another third were "taken" because they had "too much" honey but in reality it was understood that these would likely fail due to the curtailment of brood rearing. So, the numbers were reduced by two thirds in fall, but were fully expected to be increased back to the high numbers by collecting swarms. In other words, tripling one's numbers in summer was anticipated. 

In the more progressive twentieth century, beekeepers still combined colonies to increase the survival rate of the numbers overwintered. Even so, winter kill could go as high as 50 percent. It was for this reason that the package bee industry was initiated. Beekeepers could quickly restock winter losses, well in advance of and not dependent on the vagaries of natural swarming. Later, the smart beekeepers starting moving their entire holdings south to avoid the uncertainty of winter losses. And to to enjoy the warmer weather.

However, none of this should be interpreted as my saying nothing has changed. It is clear that it is more difficult to over winter colonies in cold climates due to varroa infestation. Even if varroa numbers are cut back in late summer, the colonies may have severe virus loads. These colonies may not exhibit outward signs of weakness, so the tendency is to try to overwinter anything that "looks like" it could make it. Setting oneself up to fail.

Pete

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