MR. NEWPORT ON THE TEMPERATURE OF INSECTS. 
267 
haunts of these insects, they seldom afford very satisfactory results. In order there- 
fore to ascertain the real temperature of these larvse I collected a number of separate 
nidi, each of which inclosed a larva, and placed them for a few days in a room, the 
temperature of which varied but very slightly. Each larva was then submitted to 
observation immediately it was removed from its cell. The temperature of the room 
in which the nidi were kept was 57° Fahr. The first specimen examined had been 
lying partly exposed for a short time, and the larva perhaps had thereby had its tem- 
perature diminished. When the bulb of the thermometer was inserted into its ab- 
domen the mercury rose only to 57°'8, while its external temperature was scarcely 
above that of the atmosphere. The second specimen had been better preserved from 
exposure, but the mercury rose again only to 57°'8. In a third, and apparently very 
healthy specimen, it rose to 58°. In a fourth, in every respect healthy, to 60° for 
about a moment, but rapidly sunk again to a little more than 59° ; in a fifth it rose 
also to 60° ; in a sixth to 59 0, 5 ; and in a seventh and eighth to 60°. On another oc- 
casion, when the medium in which the larvae were kept was 57°’3, the temperature of 
the under surface of a larva was 60°, but when the bulb of a thermometer was care- 
fully passed into its abdomen the mercury rose to 61° Fahr. In the larvae of Musca 
vomitoria, Linn., treated in a similar manner, the temperature of the atmosphere being 
then 56 0, 8, the mercury rose to 57°'S, but was maintained at that height only for a 
few seconds, owing to causes before noticed. 
I have not yet had an opportunity of examining the larvae of coleopterous insects, 
which judging from their similarity to those of the hymenopterous and dipterous 
classes, it is fair to infer evolve a similar amount of heat. Neither have I been able 
to examine the orthopterous and hemipterous larvae, which, from their approaching 
very near to the condition of the perfect insect, probably differ but little in their pro- 
duction of heat and the quantity of respiration. 
2. The Pupa. 
The pupa state being in all insects which undergo a complete metamorphosis a 
condition of absolute rest, the temperature of the individual is in general lower than at 
any previous or subsequent period of its existence, and is only equal to, or at most but 
very little above that of the surrounding medium. But in those insects which do not 
undergo a complete metamorphosis, the temperature probably is intermediate between 
that of the larva and perfect condition. In those species the individuals continue 
active during their whole life. These exceptions include most of the hemipterous, 
orthopterous, and a few coleopterous insects, and cannot properly be included under 
the designation of pupa, the term being here intended to apply strictly to the lepi- 
dopterous, dipterous, hymenopterous, and a few coleopterous insects. 
The only periods during which the temperature of a pupa is higher than that of 
the surrounding medium, are, first at the period of, or within a short time after its 
change from the larva state, while it is still active, and respiring very freely, and be- 
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