VORACITY OF CATERPILLARS. 197 



Portpcl leaves. Refuse. 



First age, 

 Second age, 

 Third age. 

 Fourth age, 

 Fifth age. 



Per ounce of eggs of sorted leuves, lbs 1362 142 8 

 Refuse, 142 8 



Lost from the leaves by evaporation, &c, 105 



1609~8 



He adds to this curious table, that from the 1362 lbs 

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

 sary to deduct 15.5 Ib.^, 7 oz, 4 drs of litter, consist- 

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

 and consequently that they actually devour only 1206 

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

 of this qiiantitv 74-5 li)s. 8 oz of dung are carried from 

 the hurdles; and consequentlv there is onlv digested 

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

 120 lbs of silk cocoons, — giving a loss by evaporation 

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

 nearly three parts of this loss occurring in the six last 

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

 do not alfoct the amount eaten by the caterpillars pro- 

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

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

 consumes within thirty days about 60,000 titiies 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. INlr Stephens, 

 in his valuable catalogue of British insects, a work of 



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

 Eng. Trans!. 



VOL. VI. 17* 



