272 STATES OF JNSECTS. 



causino- a rustling against the sides of the cocoon, makes 

 a considerable noise — so singular in that of a red under- 

 win«-moth (Noctua pacta), that Rosel tells us, (who by 

 the by was more timid than becomes a philosopher,) that 

 the first time he heard it, he had nearly thrown away the 

 box that contained it, in his fright a . 



vii. We are next to consider The extrication of the per- 

 fect insect from the puparinm, or pupa-case, and from the 

 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 co- 

 lours of the insect within and the motions of their li bs 

 to be distinctly seen through them. In the Libellulina 

 the eyes become more brilliant b . The mature pupae of 

 the moth lately mentioned (Eriogaster 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 [Trichoptera) push 

 off the grates from the cases which they have hitherto 

 inhabited, and swim about d . 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 pupa?, 

 the struggles of the included butterfly or moth first effect 

 a longitudinal slit down the middle of the thorax, where 



a I.iv. 101. b Reaum.vi. 407. 



e Haworth Lepidopt, Britann. i. 127. d De Geer ii. HUG, 



