STATES OF INSECTS. 235 



pulp, in the surface of which the exterior organs of the 

 adult insect cannot yet be detected. Nature requires 

 more time for their elaboration, or at least for the ap- 

 pearance of their outline, and to consolidate them. This 

 pulp first takes an oblong form {Boule allongee Reaum.), 

 and afterwards that of the insect it is destined to give 

 birth to a . The skin of the larva also serves for a cocoon 

 to the pupa? of male Cocci b . The grub of the genus An- 

 threnus, so destructive to our cabinets of natural objects c , 

 when it assumes the pupa does not quit its skin, but only 

 splits it open longitudinally on the back, and when it 

 becomes an imago makes its exit through the orifice d . 

 Some Lepidopterous larva? even (Alucita pentadactyla, 

 Callimorplia rosea, &c.) assume the pupa state within 

 their last skin e . 



When a larva has finished its cocoon, — which with 



1 N. Diet. d'Hist. Nat. xvi. 269—. xxii. 76. 



b Reaum. iv. 32. The author here quoted asserts that the grub of 

 Ichneumon Larvarum L. retains its skin, which, he says, is so trans- 

 parent that the form of the nymph can be seen through it. Ibid. ii. 

 447. De Geer, however, found that this really did cast its skin, 

 which is so transparent as to be scarcely visible, by pushing it gradu- 

 ally towards the anus, where it soon dries up and cannot then be dis- 

 covered. De Geer ii. 893 — . According to Rdsel the same circum- 

 stance attends the transformation of Coccinella renipustulata Illig. 

 (C. Cacti Ent. Brit.), which at first perplexed him not a little. It is 

 probable that in this case the retention of the skin was accidental ; 

 for some of the grubs of a Mycetophila, the transformation of which 

 I observed, became pupae within their last skin, while others wholly 

 disengaged themselves from it. The cause of this variation, I con- 

 jectured, arose from the former being too weak to extricate them- 

 selves from the skin. 



c See above, Vol. I. p. 238. Byrrhus Musceorum belongs to this 

 genus. 



d N. Did. a" Hist. Nat. ii. 161. e Pezold. 102. 



