88 Beekeeping 



laying and brood-rearing may seemingly be stimulated 

 either by a high or very low outside temperature. 



THE WINTER CLUSTER 



There are three possible ways by which an animal can 

 survive a protracted period of adversity like a northern 

 winter, when food is not available in the field and when it 

 could not get food even if it were present, because of the 

 cold. The first method is hibernation, in which the only 

 storage of food is within the animal, and at low temperatures 

 the vital functions apparently cease. This is the universal 

 mode of wintering among solitary insects and, even among 

 the social species, in bumblebees and wasps, the majority 

 of the colony die off while the fertile queens hibernate like 

 solitary insects. Ants hibernate in a mass during extreme 

 cold weather. Another method is migration, but this is 

 not open to most insects because of their size and inability 

 to fly long distances, as do birds. If a cold-blooded animal 

 cannot hibernate, as the honeybee apparently cannot, nor 

 migrate, there is but one course open to it. This is to lay 

 up a store of heat-producing food and, when the surround- 

 ing temperature falls below that at which the animal can 

 live, to generate heat, virtually to create a thermal environ- 

 ment of its own. This remarkable procedure, in which 

 the honeybee is unique among insects, is the one encountered 

 in a study of bees in winter. Beekeepers have long known 

 that the winter cluster is warm but they have perhaps failed 

 to comprehend the marvel of an insect which can use this 

 method of overcoming adverse conditions. 



The hoarding instinct, the instinct to store food in great 

 excess of the immediate needs, now becomes of vital im- 

 portance to the continuance of the species, but it would 

 serve no useful purpose in the winter season if the bees in a 

 colony did not also have the ability to generate and con- 

 serve heat. As will be seen later, the generation of heat 

 is by a method common to all insects and other cold-blooded 



