INSECTA. 349 



may be easily seen by comparing the mouth of a caterpillar with 

 that of the Butterfly, or the mouth of the larva of a Fly with that of 

 the perfect Insect. 



Several of these lame are destitute of feet; others, such as the 

 Caterpillars, have many, all, the six first excepted, membranous, 

 and without terminal hooks. Some Insects, such as the Ephemerae, 

 exhibit a singular anomaly in their metamorphosis the animal ar- 

 rived at its perfect slate undergoes another change of tegument. 



The Insects which constitute our three first orders preserve for 

 life their natal form. The Myriapoda, however, exhibit a kind of 

 metamorphosis. At first they have but six legs, or, according to 

 Savi, are altogether destitute of them; the others, as well as the 

 segments on which they depend, are developed by age. 



But few vegetable substances are protected from the voracity of 

 Insects; and as those which are necessary or useful to Man are not 

 spared by them more than others, they become very injurious, par- 

 ticularly during seasons which favour their multiplication. Their 

 destruction greatly depends upon our vigilance and knowledge of 

 their habits. Some of them are omnivorous such are the Termites, 

 Ants, &c., whose ravages are but too well known. Several of those 

 which are carnivorous, and all the species which feed on dead ani- 

 mal matters, &.C., are a benefit conferred on us by the Author of 

 Nature, and somewhat compensate for the inconvenience and injury 

 we experience from the others. Some are employed in medicine, 

 the arts, and our domestic economy. 



They have numerous enemies: Fishes destroy many of the aquatic 

 species; Birds, Bats, Lizards, &c., deliver us from a part of those 

 which inhabit the air or earth. Most of them endeavour to escape 

 by flight or running from the dangers that surround them, but some 

 have recourse to stratagem or arms. 



Having undergone their ultimate transformation, and being pos- 

 sessed of all their faculties, they continue their species: this aim 

 once accomplished, they soon cease to exist. Thus, each of the 

 three finer seasons of the year produces species peculiar to it. The 

 females and males of those which live in societies, however, enjoy 

 a longer term of life. Individuals hatched in autumn shelter them- 

 selves from the rigours of winter, and reappear in spring* 



The species, like those of plants, are circumscribed within geo- 

 graphical limits. Those of the western continent for instance, a 



