194 PTILOTA. 



servations upon the general principles of the metamorphoses, 

 noticed the peculiarities which occur in the caterpillar im- 

 mediately previous to and during its moulting. I may 

 therefore add, in order to complete the subject, that upon 

 quitting its former skin, the caterpillar appears very languid, 

 and its hody is soft and easily injured ; it speedily, however, 

 resumes its strength, and has increased so much in si/e, that 

 it appears extraordinary how it could have been packed in 

 its former covering ; its wonted voracity returns, and it now 

 feeds with redoubled energy, as if to make up for the time 

 which it had lost. 



In this manner, and for a certain period of time, the 

 growth of the insect is continued. The period which is 

 required for the arrival of the larva at its full size is very 

 variable. Perhaps the most general rule is, that insects are 

 annual in their generations; either being hatched in the 

 spring from eggs deposited in the preceding autumn, and be- 

 coming chrysalides in the course of the summer, and arriv- 

 ing at the perfect state in the autumn ; or else passing the 

 winter in the chrysalis state, and bursting forth as perfect 

 insects in the spring, and then depositing eggs, the progeny 

 of which will not require to undergo their change to pupa; 

 until the autumn. The duration of the larva state of these 

 latter will therefore necessarily be longer than in the former ; 

 but there are exceptions to these rules : thus, in many species 

 there are many generations in a year, as in the Aphides and 

 the flesh-flies ; whilst, on the other hand, some larva;, as 

 those of the goat-moth and cockchafer, require three years 

 before they attain their full growth, and the larva state of 

 the stag-beetle is stated by Rosel to extend to six years. 



Having at length attained its full size, the larva is now to 

 undergo a change more important than any to which it has 

 hitherto been subject. 



HI. The Pupa. The change to which I alluded at the 



