ON LAIiV.E. 87 



rearing of Silk-worms during their feeding period, as 

 it would secure them against those sudden atmos- 

 pheric changes which are very injurious to them, 

 and be the means of a great economy of food ; for by 

 placing the lower end of a branch of Mulberry in 

 one of the water-bottles, the leaves would be kept 

 fresh till all consumed, and at the same time be 

 rendered more healthy for the Caterpillars to feed 

 upon than half-withered ones. The greatest rapi- 

 dity of growth, however, is perhaps that which 

 takes place in a class of larvae which do not " moult" 

 — those of the House-flies, which, says Redi, become 

 from 140 to 200 times their original weight in the 

 first twenty-four hours after hatching. 



Some small larvae become larger insects in their 

 perfect state than those of greater dimensions, while 

 some of much larger size produce, after their final 

 change, insects strikingly smaller than their pro- 

 portion would lead us to expect. 



The Duration op the Larva Stage varies 

 exceedingly. That of the well-known Butterfly 

 Argynnis Faphia changes to the pupa state in 

 fourteen days ; Bees remain about twenty days in 

 the larva stage. The Cossus and the May-bug are 

 said to pass three years in the larva state ; and the 

 Beetle Orycles Nasicomis four years. The larva 



