20 BULLETIN 96, U. S. DEPARTMENT OF AGRICULTURE. 



completed until brood rearing was well established. With the estab- 

 lishment of brood rearing, the changes which manifested themselves 

 with the first eggs became intensified. The course of the temperature 

 recorded at c became unlike that which was observed in the winter 

 and was influenced more directly by the outside temperature. The 

 influence of the outside temperature became less and less marked, as 

 is shown from the fact that the oscillation of c became less and less, 

 the temperature in the center of the cluster became more constant, 

 and the temperature throughout the hive became more equalized. 

 As was stated, the turning point came on the 9th of March, but it was 

 a little more than two weeks, about the 24th or 25th of March, before 

 the colony really assumed normal summer temperature condition. 

 Once this was gained, the temperature, particularly of the center of 

 the cluster, remained relatively constant until fall. This transition 

 period of two weeks was characterized by several features. 



There was an increase of temperature both in the colony and out of 

 doors. Out of doors the maximum ranged between 12° and 18° C. 

 (53.6° to 64.4° F.), but even more favorable weather followed the 

 establishment of brood rearing and the maximum ranged from 18° to 

 25° C. (64.4° to 73.4° F.). To a certain extent the temperature of the 

 colony was raised like that of the outside temperature. The increase 

 was general throughout the colony and must be attributed to the 

 need of more heat for brood rearing, more ventilation, and the general 

 increased activity of the bees. At this time b and c ranged constantly 

 between 33° and 35° C. (91.4° to 95° F.), which will be seen to be prac- 

 tically the range throughout the summer. 



In a word, the transition from winter to summer conditions was 

 accomplished in a surprisingly short time. Accompanying incuba- 

 tion and brood rearing the temperature was gradually raised and 

 became equalized through the hive, and once well established was 

 maintained during the summer. Although the transition was rela- 

 tively abrupt, it would be expected to vary with the colony and 

 perhaps be prolonged in unfavorable weather. 



GENERAL PHENOMENA OF THE SUMMER TEMPERATURE. 



The constancy and equalization of the temperature and the range 

 of 33° to 35° C. (91.4° to 95° F.), which characterized the close of the 

 transition from winter to summer conditions, characterize equally 

 well the prevailing summer phenomena. So constant were the tem- 

 peratures in summer that their peculiarities may be briefly sum- 

 marized. Few external factors influenced the hive temperature, and 

 these affected it but slightly. In the original plan of the experiment 

 it was hoped that it would be possible to discover whether there is 

 any correlation between honey flows and temperatures ; but inasmuch 

 as the season was excessively dry and the flowers secreted no nectar 



