OF NATURAL HISTORY. 429 



female flies depofit their eggs, which, when hatched, produce new- 

 colonies, who exhibit the fame oeconomy and manners. 



There are feveral fpecies of caterpillars who are real republicans, 

 and whofe difcipline, manners, and genius, are equally dlverfified as 

 thofe of the inhabitants of different nations and climates. Some, 

 like particular favages, conftrufk a kind of hammocks, in which they 

 take their victuals, repofe, and fpend their lives till the period of 

 their transformation. Others, like the Arabs and Tartars, conftruft 

 and live in filken tents, and, after confuming the neighbouring her- 

 bage, they leave their former habitations, and encamp on frefti paf- 

 ture. Under thefe tents they are not only proteded from the inju- 

 ries of the weather, but they repofe in them when fick, or in a ftate 

 of inadivity. They go out of their tents at particular times in quefl: 

 cf food, and often to confiderable diftances ; but they never lofe their 

 way back. It is not by fight that they are direded with fo much 

 certainty to their abodes. Nature has furnilhed them with another 

 guide for regaining their habitations. We pave our ftreets with 

 ftones ; but the caterpillars cover all their roads with filken threads. 

 Thefe threads make white tracks, which are often more than a fixth 

 of an inch wide. It is by following thefe filken tracks, however 

 complicated, that the caterpillars never mifs their nefts. If the road 

 is broke by a man's finger drawn along it, or by any other accident, 

 the caterpillars are greatly embarraffed. They flop fuddenly at the 

 interrupted fpace, and exhibit every mark of fear and of diffidence^ 

 Here the march flops, till an Individual, more bold or more impa- 

 tient than his companions, travcrfes the gap. In his pafTage, he 

 leaves behind him a thread of filk, which ferves as a bridge or con- 

 dudor to the next that follows. By the progreffion of numbers,. 

 each of which fpins a thread, the breach is foon repaired. We can- 

 not fuppofe that thefe ftupid animals cover their roads to prevent 

 their wandering. But they nevsr wander, becaufe their roads are 



covei£d;i 



