STATES OF INSECTS. (Pupa.) ay | 
cocoon. The period when the pupa has attained matu- 
rity, and the inclosed insect is ready to burst the walls 
of its prison, may be often ascertained. Just at this 
time the colour frequently undergoes an alteration, the 
golden or silver tint of the gilded chrysalises vanishes ; 
and those which are transparent, usually permit the form 
and colours of the insect within and the motions of their 
limbs to be distinctly seen through them. In the Libel- 
lulina the eyes become more brilliant*. The mature 
pupe of the moth lately mentioned (L7zogaster lanestris) 
have a particular swell of the abdominal segments, not 
apparent in those that are to continue till another season, 
or longer®. ‘Those of the case-worms (TZichopéera) 
push off the grates from the cases which they have 
hitherto inhabited, and swim about °. Other signs and 
motions doubtless predict the approach of this great 
change in other species, which have not been recorded. 
The mode in which insects make their way out of the 
puparium differs in different orders. In obtected pupze, 
the struggles of the included butterfly or moth first effect 
a longitudinal slit down the middle of the thorax, where 
there is usually a suture for the purpose. The slit ra- 
pidly extends along the head, and down the parts which 
compose the breast, and the insect gradually withdraws 
itself from its case. It is not, however, from the outer 
skin merely that it has to disengage itself; but also from 
a series of inner membranous cases, which separately in- 
close the antennze, proboscis, feet, &c., as a glove does 
the fingers; and similar cases inclose the parts of the 
' 2 Reaum. vi. 407. 
* Haworth Lepidopt. Britann. i. 127. 
“ De Geer ii. 566. 
