The following post is a bit long but since it touches on both winter brood rearing and the amount of pollen in the hive, it seems worth a read.

WEDMORE (1947) says that after an autumnal period of quiescence during which the bees are avoiding the formation of a tight cluster, the onset of cold weather compels them to cluster more closely, and that this forces the temperature up at the centre of the cluster. He considers that, given adequate supplies of pollen, breeding may commence before the end of December, or as soon as the period of tight clustering sets in, in accommodation to the prevailing cold weather. From less informed sources, wider divergencies of opinion on the date of commencement of brood rearing could be quoted; and it seems desirable therefore to bring forward experimental evidence extensive enough to give an adequate picture of the real position.   

At Aberdeen the quantity of brood in the months when bees are wintering drops to a minimum in October and November. In October only one in seven of the colonies examined had brood. In November the ratio had risen to one in four, and in December and January brood was present at half of the examinations. In February and March, twelve colonies out of every 13 had some brood.  The actual quantities of brood present were almost always very small compared with summer levels [the average in December being 10 sq. ins. compared to summer often amounting to 1000 sq. ins.], and the frequency of appearance tended to increase from October onwards. With such variability of performance, however, it is hardly surprising that authors have given rather variable views on the time when bees start to breed. 

These results coincide fairly closely with Wedmore's idea of a period of quiescence followed by brood-rearing as soon as colder conditions set in; but nevertheless attempts in this laboratory to correlate the amount of brood in individual winter months with temperature fluctuations have not so far been successful. It will be noticed that these quite strong, healthy colonies had on an average only 23 sq. inches of pollen in the combs. This quantity is equivalent to 3 oz. of pollen, and is much less than Farrar considers desirable, but, under Aberdeen conditions at least, it would seem closely to represent the quantity naturally present in colonies that have not been specially manipulated in respect of pollen, and that have not been queenless during late summer. 

Unless there are wide differences in different climatic zones, it would, therefore, be reasonable to conclude that in their natural economy honeybees winter practically without any major amount of pollen (or protein) but consume only honey, a fairly pure mixture of carbohydrates: and since they would apparently have come to do this in the face of natural selection, it is perhaps a fact worth thinking about. It would seem not impossible that just as flowers have been modified by natural selection into forms which make their pollen conveniently available to bees, so the nectar of flowers may have become modified into a very pure form of carbohydrate (with in general very low levels of protein) partly because absence of protein has given the highest survival of overwintering honeybee colonies, able to continue the pollination of the flowers of succeeding seasons.

WINTER BROOD AND POLLEN IN HONEYBEE COLONIES
by EdWard P. JEFFREE, B. Sc. (Bee Besearch Department, North o] Scotland College of Agriculture, Marlschal College, Aberdeen.)
INSECTES SOCIAUX, TOME III, No. 3, 1956.
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