

96 



be enclosed in two separate cocoons. An example 

 of this may be seen in the Yellow Tussock-moth 

 (Dasychira pudilunda). 



The perfect insect extricates itself from the pupa- 

 case nearly in the same way as butterflies ; but the 

 majority have the additional task awaiting them of 

 making their way through the walls of the cocoon. 

 The firm consistence of the latter, in many instances, 

 may reasonably be supposed to render this a matter 

 of no easy accomplishment to creatures des* ; tute of 

 jaws or other instruments for eroding hard sub- 

 tances; and unless the difficulty were provided 

 against by prospective wisdom, the structures which 

 they fabricate with so much skill and labour to 

 protect them during their state of repose, would 

 often prove their tombs. It is sometimes the moth 

 that is furnished with the means of effecting her 

 own liberation, and in other cases it is provided for 

 by the caterpillar, through some peculiarity in the 

 construction of the cocoon. Of the former descrip- 

 tion are the puss-moth, and several other kinds, 

 which are provided with an acid secretion, which 

 they discharge on the end of the cocoon from which 

 they desire egress, and by its solvent power the com- 

 pact wall soon loses its cohesion and gives way to 

 the slightest pressure. Others possess the means of 

 breaking the threads at one end, employing for that 

 purpose, according to Reaumur's opinion, the minute 

 facets of the eyes, which are the only hard organs 

 in the head, after the manner of a file. Generally 

 however, the texture is loosened by some solvent 



