ENTOMOLOGY. S3 



nieiits of munducation are strong and efficient; the 

 digestive organs greatly developed, and the skin perio- 

 dically thrown off to remove any impediment to the 

 distention of the body. The consumption of food is 

 necessarily great,, in some cases exceeding that of 

 any other animals, regard being had to their respec- 

 tive size. In fact, many of the kinds which consume 

 the foliage of plants eat with little intermission ; and, 

 in some instances, they continue to feed both by night 

 and day. The growth of the larvae of flesh-flies 

 (^Sarcophaga) is unusually rapid, some of them having 

 been found to become 200 times heavier in twenty- 

 four hours. When it has attained its foil growth, 

 the caterpillar of the goat moth is sometimes 72,000 

 times heavier than when newly hatched. The ex- 

 periments of Count Dandalo on the silk-worm, make 

 it appear that when just hatched, this caterpillar is a 

 line in length, and a hundred weigh about a grain ; 

 after the first moulting, the length of each is four 

 lines, and a hundred weigh fifteen grains; after second 

 moulting, length 6 lines, weight 94 grains ; after third 

 moulting, length 12, weight 4-00 ; after fourth moult- 

 ing, length 20, weight 1628; after fifth moulting^ 

 the length of each is upwards of three inches, and a 

 hundred weigh about 9500 grains. 



The number of these moultingsor changes of skin 

 varies greatly in different insects, but it is always alike 

 in the same species. The intervening periods like- 

 wise vary, being dependent on the length of life 

 allotted to the larvae. In the silk worm, as has just 

 feeen seen, the moultings are five, and aU these occur 



