PRODUCTION OP HEAT BY INSECTS. 337 



in a state of activity, that it might be at such times called a 

 warm-blooded animal ; though in the states of abstinence, 

 sleep, and inactivity, its temperature falls again nearly to that 

 of the atmosphere. A single Humble-bee, inclosed in a phial 

 of the capacity of 3 cubic inches, had its temperature speedily 

 raised by violent excitement, from that of rest (2 or 3 above 

 that of the atmosphere) to 9 above that of the external air ; 

 and communicated to the air in the phial as much as 4 of 

 heat within five minutes. In another similar experiment, the 

 temperature of the air in the phial was raised nearly 6 in 

 eight minutes. It is among the active Butterflies, and the 

 Hymenopterous insects (Bee and Wasp tribe), which pass 

 nearly the whole of their active condition on the wing, that 

 we find the highest temperature ; and next to them are the 

 more active of the Beetle tribe. Those of the latter which 

 seldom leave the ground, have little power of producing heat. 

 411. The greatest manifestation of this power is shown 

 among Insects which live in societies ; most of which belong 

 to the order Hymenoptera. It has been seen that the body 

 of a Humble-bee, in a state of activity, has a temperature of 

 about 9 above that of the atmosphere ; but its nest has been 

 found to have an ordinary temperature of from 14 to 16 abova 

 the air, and from 17 to 19 above that of the chalk bank in. 

 which it was formed. The production of heat is increased 

 to a most extraordinary degree, when the pupae are about to 

 come-forth from their cells as perfect Bees, requiring a higher 

 temperature for their complete development. This is fur- 

 nished by a set of Bees termed Nurse-bees, which are seen 

 crowding upon the cells and clinging to them, for the purpose 

 of communicating to them their warmth; being themselves 

 evidently very much excited, and respiring rapidly, even at 

 the rate of 130 or 140 inspirations per minute. In one 

 instance, the thermometer introduced amongst seven nursing- 

 bees stood at 92|, whilst the temperature of the external air 

 was but 70. In Hive-bees, whose societies are large, this 

 process occasions a still more remarkable elevation of tempe- 

 rature ; for a thermometer introduced into a hive during May 

 has been seen to rise to 9 6 or 98, when the range of atmospheric 

 temperature was between 56 and 58. In September, when 

 the bees are becoming stationary, the temperature of the hive 

 is but a few degrees above that of the air. It was formerly 



