268 
MR. NEWPORT ON THE TEMPERATURE OF INSECTS. 
fore it has completely subsided into a state of rest. At that time, when the whole of 
its energies are called into activity in effecting its transformation, the temperature of 
the pupa may be considerably higher than that of the surrounding medium. Thus I 
have found it in the Sphinx, immediately after changing, equal to that of the active 
larva. When the temperature of its cell in the earth was 68°'3, the temperature of 
the newly-changed pupa within it was 69° - 5, a difference of 1 0, 2 ; but within a single 
hour afterwards, while the body of the pupa was yet soft, the difference was scarcely 
more than three tenths of a degree. So likewise when a pupa is very much disturbed 
for the purpose of experiment, its temperature becomes considerably increased. Also 
when the medium in which the pupa is living is suddenly diminished, or when the 
pupa is removed from a warmer to a colder medium; and lastly, when the pupa, 
aroused by the stimulus of gradually increasing external temperature, begins again 
to respire freely, during a short time before it is developed into the perfect insect. 
In each of these cases its temperature may be more or less high, according, in the 
first place, to the rapidity with which the temperature of the surrounding medium 
has been diminished, and in the second according to its quantity of respiration in a 
given time. The increased temperature of a lepidopterous pupa arising, as it appears 
to do, with increased respiration, is coincident with the power which the insect gra- 
dually acquires before it is able to fissure its prison-house and liberate itself from the 
puparium ; while the hymenopterous insect, which lives in society, and remains during 
its nymph or pupa state inclosed in an almost impervious cocoon, has its tempera- 
ture artificially increased by the incubation of insects already developed. 
It is very shortly after an insect has entered the pupa state that its respiration is 
diminished, and its temperature sinks down very nearly to that of the surrounding 
medium. At 8 a.m., November 10, two pique of Sphinx ligustri, which had remained 
during several weeks with other specimens entirely undisturbed, were carefully re- 
moved with the forceps into glass-stoppered phials, the temperature of which was 
exactly that of the room in which the pupa had previously been kept. They were 
examined during three succeeding days, the temperature of the atmosphere being also 
very carefully noted. The temperature of the phials varied a little, but there was not 
the slightest difference between the temperature of the atmosphere of the phials and 
of their respective pupse, even when the thermometer was allowed to remain in con- 
tact with the pupse for several minutes. The variations in the temperature of the 
phials are shown in the following Table. 
Table I. Temperature of Pupse. 
Period of observation. 
Atmosphere. 
Phials. 
Diff. 
Remarks. 
Nov. 10, 1834. A.M. 8 
o 
53-4 
No. 1. 53-4 
f 
No. 2. 53-4 
r.M. 1£ 
54-5 
No. 1. 54-7 
•2 
Pupa had been a little excited. 
f 
No. 2. 54-5 
11 r.M. 1 
51-5 
No. 1. 51-6 
•1 
Atmospheric temperature sinking. 
s 
No. 2. 51-6 
•1 
12 A.M. 9 
51-9 
No. 1. 51-8 
Atmospheric temperature rising. 
No. 2. 51-9 
13 A.M. 9$ 
50-9 
No. 1. 51 
•1 
Atmospheric temperature sinking. 
1 
No. 2. 51-1 
•2 
