62 THE CLASS OF INSECTS. 



are gradually released, and with them the antennae, palpi, and 

 legs, and tlie lar^a removes itself entirely from the shell and 

 membranes. In this process of evolution the young MeJo'e 

 throws off two distinct co\erings : first, the sliell with its lining- 

 membrane, tlie analogue of the membrane in which, as I have 

 elsewhere sliown,* the 3-ouug M^riopod is inclosed, and re- 

 tained several days after tlie bursting of the ovum, and which 

 represents in the Articulata, not the allantois, but npparently 

 the amnion, of Vertebrata ; next, the first, or fa'tal deciduation 

 of the tegument, analogous probably to the first change of skin 

 in the Myrlopod, after it has escaped from the amnion, and 

 also to the first change which the young Arachnidan invariably 

 undergoes a few days after it has left the egg, and before it 

 can take food. This tegument, which, perhai)s, may be analo- 

 gous to the vernix caseosa of Vertebrata, thrown off at the 

 instant of birth, is left by the 3'oung jNIeloe with the amnion 

 in the shell ; and its separation from the body, at this early 

 period, seems necessarj' to fit the insect for the active life it 

 has commenced." (Linn. Trans, xx. p. 30G, etc.) 



The larva state. The larva (Latin larva^ a mask) was so 

 called because it was thought to mask the form of the perfect 

 insect. The larvae of Butterflies and Moths are called cater- 

 pillars; those of Beetles, <7r;<&s; and those of the two-winged 

 Flies (Diptera) maggots; the larvae of other groups have no 

 distinctive common names. 



As soon as it is hatched the larva feeds voraciously, as if in 

 anticipation of the coming period of rest, the pupa state, for 

 which stores of fat (the fatty bodies) are dcAeloped for the 

 supply of fat globules out of which the tissues of the new 

 body of the pupa and imago are to be formed. 



Most larviii moult, or change their skin, four or five times. 

 In the inactive thin-skinned larvae, such as those of Bees, 

 AYasps, and Gall-flies, the moults are not apparent ; as the 

 larva increases in size it out-grows the old skin, which comes 

 off in thin shreds. But in the active larvse, such as cater- 

 pillars, grasshoppers, and grubs, from the rapid absorption of 

 vessels in the outer la3'er of the skin, just before the change, 



* Philosophical Transactions, Pt. 2, 1841, p. 111. 



