THE METAMORPHOSIS OF INSECTS. 237 



said, " Were a naturalist to announce to the world the 

 discovery of an animal which for the first five years of 

 its life existed in the form of a serpent ; which then, pene- 

 trating into the earth, and wearing a shroud of pure silk 

 of the finest texture, contracted itself within this cover- 

 ing into a body without external mouth or limbs, and re- 

 sembling more than any thing else an Egyptian mummy ; 

 and which, lastly, after remaining in this state for three 

 years longer, should, at the end of that period, burst its 

 cerements, struggle through its earthy covering, and 

 start into day a winged bird, what would be the sensa- 

 tion excited by this piece of intelligence ?" And yet this 

 would be no more wonderful than the ordinary metamor- 

 phosis of Insects. Indeed, many of the most marvelous 

 circumstances in this change are not at all referred to in 

 the supposition above made. 



406. The larva is produced from an egg, and the egg 

 is laid by the perfect Insect or Imago. When the larva 

 is first hatched it is very small, but it grows with a ra- 

 pidity always great, in some cases enormous. The mag- 

 gots of flesh Flies are said to increase in weight two 

 hundred times in twenty-four hours. To make such an 

 increase these animals must eat voraciously. With the 

 great multiplication of their number, the amount which 

 a collection of them will sometimes devour is wonderful. 

 Linnaeus calculated that three flesh Flies and their imme- 

 diate progeny would eat up the carcass of a horse sooner 

 than a lion would do it. 



407. In the Imago state the Insect eats but little, as it 

 grows little or none ordinarily. The Butterfly or Moth 

 comes forth from its prison fully grown ; but the cater- 

 pillar from which it was formed was very small at the 

 outset, and became large by large eating. Our common 

 Flies are small and delicate eaters, but the Maggots, the 

 larvae from which they came, rioting in filth, devour 

 largely what the Flies will not touch,, 



408. The great growth of larvae obliges them to cast 



