STATES Ol- INSECTS. J 99 



been enlivened by exposure to the air, when they become 

 more fresh, vivid, and beautiful to appearance than ever. 

 When a few meals have invigorated its languid powers, 

 the renovated animal makes up for its long abstinence 

 by eating with double voracity. 



A similar preparatory fast, and succeeding state of 

 debility, accompany every change of the larva's skin. 

 Each time except the last, the old skin is succeeded by 

 a new one, with few exceptions, similar to the one it has 

 discarded. Previously to the final change, which discloses 

 the pupa, it quits the plant or tree on which it had lived, 

 and appears to be quite unsettled, wandering about and 

 crossing the paths and roads, as if in quest of some new 

 dwelling. It now abstains from food for a, longer time 

 than before a common moult, empties itself copiously, 

 and as I have just said, if Swammerdam and Bonnet are 

 to be depended upon, casts the skin that lines the sto- 

 mach and intestines, as well as that of the Tracheae. 



I have observed above, that all larvae, with few excep- 

 tions, change their skins in the manner that I have de- 

 scribed. These exceptions are principally found in the 

 order Diptera, of which those of the Linnean genera 

 Musca, (Estrus, and probably all that, like the maggot 

 of the common flesh-fly, have membranous contractile 

 heads, never change their skin at all, not even prepara- 

 tory to their becoming pupae. The skin of the pupa, 

 though often differing greatly in shape from that of the 

 larva, is the same which has covered this last from its 

 birth, only modified in figure by the internal changes that 

 have taken place, and to which its membranous texture 

 readily accommodates itself The larvae of* the Dipte- 

 rous genera Tipula, Cidej^ and those which have corne- 



