240 INSECTA. 



the others, as well as the segments on which they depend, are 

 developed by age. 



But few vegetable substances are protected from the vora- 

 city of Insects ; and as those which are necessary or useful to 

 Man are not spared by them more than others, they become 

 very injurious, particularly 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 ra- 

 vages are but too well known. Several of those which are 

 carnivorous, and all the species which feed on dead animal 

 and excrementitious mattei's, are a benefit conferred on us by 

 the Author of Nature, and somewhat compensate for the incon- 

 venience 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 ilight or running from the dangers 

 that surround them, but some have recourse to stratagem or 

 arms. 



Having undergone their ultimate transformation, and being 

 possessed of all their faculties, they hasten to propagate their 

 species : — this aim once accomplished, they soon cease to 

 exist. Thus, each of the three finer seasons of the year pro- 

 duces 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 themselves from the 

 rigours of winter, and reappear in spring. 



The species, like those of plants, are circumscribed within 

 geographical limits. Those of the western continent for in- 

 stance, a very few, and all from the north, excepted, are 

 strictly peculiar to it ; such also is the case with several ge- 

 nera. The eastern continent, in turn, possesses others which 

 are unknown in the western. The Insects of the south of Eu- 

 rope and north of Africa, and of the western and southern 

 countries of Asia, have a strong mutual resemblance. The 



