CLASS INSECTA. 21 



Their first slate is named larva ; the second, 7iympha ; the 

 third, perfect state {imago). It is only in this last that 

 they are capable of reproduction. 



All insects do not pass through these three states. Those 

 which have no wings leave the egg with the form which they 

 are always to preserve.* These are called insects without 

 metamorphosis. Among those which have wings, a great 

 number undergo no other change than this acquisition. Their 

 larva resembles the perfect state, with the exception only of 

 the wings, which are wholly wanting. The 7iymph does not 

 differ from the larva but in the rudiments of wings, which 

 in the last change are developed to place the insect ia its 

 perfect state. Such is the case with bugs, locusts, &c. 

 Finally, with the rest of the winged insects in which the 

 metamorphosis is complete, the first state is a larva, formed 

 like a caterpillar or worm, the second, a motionless nympha, 

 in which, however, all the parts of the perfect insect exist, 

 but in a contracted state. 



These parts are free, although closely approximating to 

 each other, and fixed against the body, in the nymphae of 

 the coleoptera, the neuroptera, the hymenoptera, &c. ; but 

 they are not so in those of the lepidoptera and of many in- 

 sects with two wings. An elastic skin, or one of a consistence 

 tolerably firm, is moulded over the body and its external 

 parts, or forms for it, as it were, a sort of case. 



That of the nymphas, or chrysalids of the lepidoptera, con- 

 sisting only of a simple pellicle, applied on the external 

 organs, following all their contours, and forming for each of 

 them so many special moulds, like the envelope of a mummy, 

 enables us directly to recognize and distinguish them, {pupa 

 obtecta, Lin.) But those flies, &c. formed of the dried skin 



* The Jlea, the females of the mutilla, and the tvorking ants, with a 

 very few other insects, excepted. 



