PRODUCTION OF HEAT BY INSECTS. 
337 
in a state of activity, that it might he 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° above 
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 
eome-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 
z 
