MR. NEWPORT ON THE TEMPERATURE OF INSECTS. 
273 
activity, its temperature gradually subsides, and continues to be diminished in pro- 
portion to the length of time it remains inactive, until it has approached very near to 
the temperature of the atmosphere. Thus many of those insects which have a com- 
paratively high temperature when in a state of active exertion in the early part of the 
summer, have their temperature greatly reduced when they become inactive at the 
end of autumn ; and when an insect passes from a state of inactivity into that of na- 
tural sleep, its temperature subsides even during summer, very nearly to that of the 
surrounding medium. This was the case with the larvse of Sphinx Atropos and 
Bomhyx hucephala, as shown in the observations on larvse. 
3. Sleep . 
All insects enjoy a periodical state of repose, or natural sleep. They are endowed 
with this privilege of life for the renovation of their voluntary energies in common 
with other animals. It is at this period that the involuntary functions of the body, 
which, together with the voluntary, are exercised to their utmost amount during the 
willing activity of the individual, begin steadily to subside, in order to restore the 
equilibrium which ought to exist between the healthy capability of the organs em- 
ployed and the amount of energy expended. Respiration, circulation, digestion, 
and the evolution of animal heat are all diminished, until a fresh amount of voluntary 
power is again generated, and the animal is aroused to the enjoyment of it either 
by its superabundance, or through the agency of external stimuli. It is no small 
amount of this privilege that is enjoyed by insects. I have witnessed sleeping in 
almost every order of insects, and am satisfied that they enjoy as great a proportion 
of rest as any other animals. Many insects will remain in a state of rest during ten, 
twelve, or twenty hours at a time, even in their seasons of activity, influenced as 
they are by external stimuli. Every one is aware that the common May Chaffer, Me- 
lolontha vulgaris, will often continue sleeping on the leaves of the lime tree throughout 
the whole of a fine summer’s day, and not become active until near sunset. The case 
is the same with nearly the whole tribe of Sphinges and Moths, while many Butter- 
flies which are active during sunshine, will often remain for two or three days, when 
the weather is gloomy, affixed to the very same spot. The common Honey Bee, Apis 
mellifica, Linn., notwithstanding the bustle and activity of the hive, enjoys its share 
of repose as well as other insects, even amidst the apparent commotion of its own 
dwelling. Huber observed that his bees often inserted their heads and part of their 
bodies into the empty combs, and remained there for a considerable time. They 
were then quietly sleeping in the cells. At other times they appear to sleep for short 
intervals on the surface of the combs. I have seen them towards the latter end of 
summer sleeping in the cells in great numbers for many hours together. It is there 
also where many of them pass a portion of their winter, doubtless in a state of hyber- 
nation, or most profound sleep ; and it is an interesting fact, that this inactivity of 
the inhabitants of the hive during winter, is accompanied by a diminution of heat in 
