60 OF THE LARVA STATE. 



seventy-two thousand times heavier than when it 

 emerges from the egg ; and the maggot of the Blue 

 Fly is, in twenty-four hours, one hundred and fifty-five 

 times heavier than at its birth. 



Caterpillars have sixteen legs, and devour their 

 food by means of two jaws ; they have twelve eyes, 

 so exceedingly minute, as to be nearly imperceptible 

 without the aid of a microscope. 



The quantity of food which is daily eaten by a 

 caterpillar is surprising, being greatly more in pro- 

 portion to its bulk than is consumed by any other 

 animal. Many larvae eat twice their own weight of 

 leaves within twenty-four hours. John Hunter assigned 

 as a cause, that their stomachs have not the power of 

 dissolving vegetable matters, but merely the faculty of 

 extracting a juice from them.* This seems indisputable 

 from the faeces, consisting of coiled up hardened par- 

 ticles of leaves, which, after being immersed in water, 

 will expand like tea leaves. The quantity, also, in pro- 

 portion to the mass consumed, is farther confirmation 

 of the fact. Colonel Marshall made some detailed 

 experiments, and found that the larva of the Bombyx 

 caja, which weighed thirty-six grains, voided every 

 twelve hours from fifteen to eighteen grains weight 

 of excrement ; while it only increased in weight 

 during that time from one to two grains. While in 

 this condition they generally eat voraciously, and 

 Depose but for short intervals. As they enlarge? 

 which they to very rapidly, they cast their skins 



* Observations on the Animal Econcmy, p- 221. 



