The Cycle of the Year 89 



animals while the conservation of heat depends chiefly on 

 the structure of the winter cluster. 



When the last brood has emerged, the colony and its 

 nest are then in condition to pass the winter. In cold 

 weather the bees form a single compact cluster and leave 

 the hive only on occasional warm days for cleansing flights. 

 Bees do not discharge their feces in the hive so long as they 

 are in normal, healthy condition but> after even a short 

 confinement, will venture out for this purpose as soon as 

 the outside temperature permits. 1 



Movements in winter. 



The cluster is first normally formed where the last brood 

 emerged; here the bees find empty cells into which to 

 crawl, so that they form themselves into a compact mass, 

 separated only by thin walls of wax. They do not form 

 the winter cluster where the combs are filled with honey 

 and it would probably be impossible for them to conserve 

 the heat of the cluster if sheets of honey separated the bees 

 in adjacent spaces. As the contiguous stores -are consumed 

 and additional cells are emptied, the cluster is shifted so 

 that the bees are always near stores. This shifting is, how- 

 ever, apparently impossible in extreme cold weather, when 

 colonies sometimes die in a way that can be explained only 

 as due to starvation through inability to reach stores just 

 a few inches distant. The early fall cluster is usually low 

 on the combs, near the entrance, if there is considerable 

 honey stored and the movement of the cluster is usually 

 upward and toward the rear of the hive as winter progresses, 

 and as stores are consumed. If a colony is in a two-story 

 hive, the cluster is often in the upper story in the spring. 



Responses to outside temperature. 



The cluster varies in size with the outside temperature. 

 After the emergence of the last brood in the fall, if the 



1 Bees often remain in the hive at a temperature of 70 F. if a flight is 

 not necessary, but will often fly when the temperature is about 50 F. if 

 they have been confined for a time. 



