AND THE LOWER ANIMALS. 75 



done, it flies away and speedily perishes. Once it lias 

 gone, the caterpillar no longer exhibits any symptom 

 of suffering. Its wounds are healed, and it prepares 

 to undergo its first metamorphosis, just as if nothing 

 had occurred; but it undergoes no further develop- 

 ment, and instead of a butterfly there spring from the 

 chrysalis as many little maggots as there had been eggs. 



In fact each of these eggs has produced a larva, 

 with a smooth white body entirely devoid of limbs, 

 and whose head, concealed in part by a sort of hood, 

 is provided with a chewing apparatus well calculated 

 to divide the caterpillar's tissues. These larvae begin 

 gnawing around them, at first carefully avoiding 

 the more essential organs, and attacking only 

 the fatty structures which surround and connect 

 them. Afterwards having become more voracious, 

 and just as their involuntary nurse has completed its 

 growth and transformation, they devour everything 

 remaining, and then piercing the skin which they 

 have emptied of its contents, they come out and spin 

 their pretty little yellow cocoons. In these they pass 

 the winter without undergoing any alteration in form ; 

 but by the time spring arrives they have become 

 piypce, and a few days subsequently they appear as 

 perfect winged insects. 



Twenty or twenty-five — in other words about half of 

 this brood — are perfect females, who very soon sacrifice 

 as many caterpillars to the production of their off- 

 spring. We now see how the Pierides are destroyed 

 by the Microgaster. Reaumur calculated that at 

 least nine-tenths of all the ova are lost in this way, 

 and of two hundred pupae collected by M. Blanchard, 

 only three gave rise to butterflies; the remaining 



