The Cycle of the Year 59 



THE TEMPERATURE OF THE HIVE 



In a study of the activities of a colony of bees, the question 

 of temperature must be carefully considered. Bees are cold- 

 blooded (poikilothermous) animals, that is, the temperature 

 of the body of an individual bee is variable and is the same 

 or almost the same as that of the air immediately surround- 

 ing the body. All cold-blooded animals usually have a 

 temperature slightly above that of the surrounding medium, 

 except in the case of animals having a moist skin and sur- 

 rounded by air, in which evaporation on the surface of the 

 body may cause the temperature of the body to fall a little 

 below that of the air. The heat which raises the tempera- 

 ture of the individual bee, and collectively of the bee colony, 

 above that of the surrounding air is generated chiefly by 

 muscular activity. The individual bee can continue mus- 

 cular movements only so long as the temperature of the body 

 does not fall below 45° F., but at about this temperatiu'e it 

 loses its power of movement. The highest temperature at 

 which bees can live has not been accm'ately determined but 

 it must be over 130° F. 



While the individual bee does not possess the abiUty to 

 maintain a nearly uniform body temperature, as do warm- 

 blooded animals, the colony as a whole shows some remark- 

 able temperature changes, different from any observed in 

 individual bees or in other cold-blooded animals. Warm- 

 blooded animals maintain a fairly constant temperature 

 which may be either higher or lower than that of the sur- 

 rounding air. While the colony of bees may maintain a 

 temperature either warmer or colder than the surrounding 

 air (colder than the air outside the hive), the temperature 

 of the colony is not constant. In warm-blooded animals, 

 most of the heat is generated by the processes of internal 

 combustion in the assimilation of food, augmented by heat 

 due to muscular activity. In the bee, the chief method of 

 heat production is by muscular activity, with possibly some 

 additional heat from other life processes, and the bee, unlike 



