VORACITY OF CATERPILLARS. 197 



Sorted leaves. Refuse. 



Ibs oz Ibs oz 



First age, 60 18 



Second age, 18 30 



Third age, 60 90 



Fourth age, 180 27 



Fifth age, 1098 102 



Per ounce of eggs of sorted leaves, Ibs 1362 142 8 

 Refuse, 142 8 



Lost from the leaves by evaporation, &c, 105 



1609~~8 



He adds to this curious taj)le, that from the 1362 Ibs 

 of sorted leaves given to the caterpillars, it is neces- 

 sary to deduct 155 Ibs, 7 oz, 4 drs of litter, consist- 

 ing of fragments of uneaten leaves, stalks, fruit, &c, 

 and consequently that they actually devour only 1206 

 Ibs, 4 oz, 4 drs. It is necessary also to mention that 

 of this quantity 745 Ibs, 8 oz of dung are carried from 

 the hurdles; and consequently there is only digested 

 771 Ibs, 7 oz, 4 drs of pure leaves, which produce 

 120 Ibs of silk cocoons, giving a loss by evaporation 

 from the worms in gas and vapour of 496 Ibs, 4 oz, 

 nearly three parts of this loss occurring in the six last 

 days of the fifth age.* These deductions, however, 

 do not affect the amount eaten by the caterpillars pro- 

 duced from 1 oz of eggs, which is upwards of 1200 

 Ibs. A single silk-worm, as we before mentioned, 

 consumes within thirty days about 60,000 times its 

 primitive weight. 



When we take these facts into consideration, we 

 need not be surprised at the extensive ravages com- 

 mitted by other caterpillars, many of which are much 

 larger than the silk-worm, and all of them produced 

 in broods of considerable numbers. Mr Stephens, 

 in his valuable catalogue of British insects, a work of 



* Count Dandolo's Art of rearing Silk- Worms, p. 322-24, 

 Eng. Transl. 



VOL. VI. 17* 



