364 RAVAGES OF INSECTS. 



quantity of leaves drawn from the tree employed for each 

 ounce of eggs amounts to 1609 lbs. 8 oz., divided in the 

 following manner :" — 



Sorted leaves. Kefuse. 



lbs. oz. lbs. oz. 



First age G 1 8 



Second age 18 8 



Third age GO 9 



Fourth age 180 27 



Fifth age 1098 102 



Per ounce of eggs of sorted leaves . lbs. 13G2 142 8 



Eefuse 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 necessary to 

 deduct 155 lbs. 7 oz. 4 drs. of litter, consisting 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 quantity 745 lbs. 8 oz. 

 of dung are carried from the hurdles ; and consequently 

 there is only 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 affect the amount eaten by the caterpillars produced 

 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 times its primitive weight. 



When we take these facts into consideration, we need 

 not be surprised at the extensive ravages committed by 

 other caterpillars, many of which are much larger than the 

 silk-worm, and all of them produced in broods of consider- 

 able numbers. Mr. Stephens, in his valuable catalogue of 

 British insects, a work of very extraordinary accuracy, 

 enumerates nearly 2000 species of native moths and butter- 



* Count Dandolo's Art of Bearing Silk-Worms, p. 322-24, Eng. Transl. 



