M 



THE VICTORIAN NATURALIST. 



or in part from their old skin in the shell itself, but the imago is 

 still a prisoner. It has broken through a first enclosure ; it must 

 open itself a way through the second. How does it manage to 

 bore through the often very solid walls of this second prison, so 

 as to regain its liberty ? " 



Reaumur states that in the Lackey Moth (Bombyx 

 neustria) the head is the only instrument of which the 

 insect makes use in opening a passage, the compound 

 eyes then acting like files. These files cut the very fine 

 threads of which the cocoon is composed, and as 

 soon as the end of the cocoon is pierced through, 

 the insect uses its thorax like a wedge to enlarge 

 the hole. The Lackey Moth, however, only con- 

 structs a leathery sort of cocoon, so that, even 

 if Reaumur's explanation is correct, it would 

 hardly apply to such species as the European 

 Puss Moth ( Dicranura vinula) or our own 

 Anther cea eucalypti, which constructs for its cocoon 

 those hard oval excrescences so familiar on our 

 young gum trees. 



The largest amount of information on the 

 subject I found in that most delightful of works 

 to an entomologist, " The Introduction to Ento- 

 mology," by Kirby and Spence, in their chapter 

 on the extrication of the perfect insect from the puparium, or 

 pupa case, and from the cocoon. Under this heading they deal 

 very exhaustively, and I believe correctly, with most families, and 

 I shall quote them somewhat freely later on. 



Now, although we could very profitably and pleasantly devote 

 some time to the various descriptions of pupse and cocoons, as 

 this paper more particularly concerns those enclosed in hard 

 coverings, we shall only need to refer to the others very slightly. 



The greater number are very simple, and include the butter- 

 flies, the Geometers, and most of the Noctuas. In these forms, 

 when the enclosed insect is ready to emerge, its struggles, and a 

 certain amount of inflation it is capable of, cause the pupa case 

 to split down the thorax, and the insect then forces its way out, 

 the case having become very thin and fragile ; sometimes, instead 

 of splitting down the thorax, the entire covering of the legs and 

 antennae is thrust out, but in either case the operation is easy, 

 and, the pupa case once broken, the moth or butterfly has nothing 

 more to do than to suspend itself in a convenient posture and 

 develope its limp wings. 



The species inhabiting reeds or trees are furnished with spines 

 or bristles on the segments, which enable them to work their way 

 to the exit previously prepared by the larva, while subterranean 

 pupai likewise have the power of working towards the surface, 



Cocoon of 

 A . eucalypti. 





