THE TEMPERATURE OF THE BEE COLONY. 



11 



active portion of the cluster has a higher and more uniform tempera- 

 ture than the other parts, while the outside layers are subject more 

 directly to the fluctuations of the winter weather. Most of the fol- 

 lowing study of the winter conditions of the beehive will be based on 

 the records of the center of the cluster. 



It would naturally be expected that the heat radiating from the 

 bees would tend to delay the effects of the penetration of the cold of 

 the outside air on the cluster. In other words, it might readily be 

 expected that the cluster thermometers would reach their maxima and 

 minima later than the outside thermometer. However, this occurred 

 seldom and only in severe weather, when the changes were rapid and 

 considerable. Even then there was a delay of only an hour or two 



at the most. This 

 again suggests the 

 sensitiveness and 

 the responses of the 

 cluster to the 

 changes in the ex- 

 ternal air. The ad- 

 aptation of the bees 

 to changes in the 

 atmospheric condi- 

 tions will be more 

 apparent when de- 

 tails are considered. 

 As has been sug- 

 gested above, there 

 was a tendency for 

 the cluster gradu- 

 ally to maintain a 

 higher temperature 

 as the season ad- 

 vanced toward spring and the beginning of egg laying. The schematic 

 curve, figure 7, presents graphically the conditions of temperature at 

 thermometer c throughout the winter. It will be noticed that dur- 

 ing the month of November, when the bees were less definitely and 

 constantly clustered, the amplitude of the daily variation and the 

 general temperature of the cluster were higher than in the succeeding 

 months. This is also evident in the fact that the curve of the ther- 

 mometer c at this time of the winter tended to follow the curve of 

 the outside thermometer o to some extent. In December, however, 

 there was a change in the course of the temperatures at c, in response 

 to the change in outside conditions. The conditions remained more 

 nearly constant from this time until egg laying commenced in the 

 spring, except that as the weather tended to warm up at the approach 



Fig. 7. — Schematic curve showing cluster temperatures of the bees dur 

 ing the winter and after brood rearing began. 



