270 
MR. NEWPORT ON THE TEMPERATURE OF INSECTS. 
by the greater rapidity with which insects in the condition of nymphs part with their 
natural heat than even the larva ; and this apparently is the reason why most hyme- 
nopterous insects select those situations for their young which are found to be the 
worst conductors of heat. This evidently is why the Anthophora incloses its larvae 
in cells constructed in the vertical sections of banks of earth which are exposed to 
the morning sun, and why the Hive and Humble Bees crowd over those cells 
which are about to produce the perfect insect, when the inclosed nymphs are most in 
need of increased temperature to invigorate them for the change they are about to 
undergo. 
3. The Imago, or Perfect State. 
When an insect has assumed its last or perfect condition it has a higher tempera- 
ture of body than at any other period of its life, and when in a state of activity is not 
so much influenced by sudden changes of atmospheric temperature as in its earlier 
states of existence as larva or pupa ; and it has also a greater power of generating as 
well as of maintaining its temperature. But it is not until some time after an insect 
has assumed its perfect form that it is able to support its full temperature. This 
period is longer or shorter, according to the habits of the species. When a lepido- 
pterous insect leave its puparium with its whole body soft and delicate, and its wings 
undeveloped and hanging uselessly like little buds from the sides of its thorax, it so 
rapidly parts with its temperature that it appears to have a lower degree of heat than 
at the time when it was about to pass from the larva to the pupa state, and it imme- 
diately seeks a retired situation, where it may suspend itself vertically at rest, and 
complete the development of what are now to become its most important organs of 
locomotion. In effecting this development it is well known that the insect first begins 
to breathe very deeply, and it continues to do so for a considerable time. The in- 
spired air passes from the large air-sacs in the abdomen of the insect into the base of 
the wings, with which the air-sacs have a direct communication* ; and while the 
ramified tracheae in the wings are becoming elongated and distended, and the wings 
in consequence developed, the temperature of the insect again begins to increase. 
But it is not until the wings have become firm and fitted for flight that the insect is 
enabled to generate its full amount of temperature. Thus in the Puss Moth, Centra 
vinula, Steph. half an hour after coming from the pupa the temperature of the insect 
was only "2 of a degree above that of the atmosphere ; at an hour afterwards - 3 ; at 
an hour and a half - 6. During this period the insect was only in a moderate state of 
activity. But at two hours and a half, and when a little more active, its temperature 
amounted to one degree and two tenths ; and on the following day, when perfectly 
strong and excited as during rapid flight, it amounted to nearly 7° above that of the 
atmosphere (Table V. Nos. 25 to 35.). 
This is exactly the same with the Sphinx ligustri, *Lii$N. An individual which had 
* Mr. Goadby, Medical Gazette, April 2, 1836. 
