62 



INSECT TRANSFORMATIONS. 



stance, indeed, of the whole phenomenon, is the in- 

 stinct with which the grubs are evidently guided to 

 avoid devouring any vital part, so that they may not 

 kill the caterpillar, as in that case it would be useless 

 to them for food. When full grown, they even eat 

 their way through the skin of the caterpillar without 

 killing it; though it generally dies in a iew days with- 

 out moving far Irom the place where the grubs have 

 spun their group of silken cocoons in which to pass the 

 winter. 



Ccnerartion of Ichneumons. « «, the caterpillar of Poniia Brnssiccc. 

 fe, the epgs of that butterfly glued to a leaf c, Micrognittr glomcratus, 

 magnified, d d d, a magnified view of a dissected cfiterpillar, in whose 

 body a number of ichneumon caterpillars have been hatched, e, silk co- 

 coons spun by the ichneumons. /, grubs spjiming cocoons, g, grubs 

 eating their way out of the caterpillar. 



