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 few days with- 

 out moving far trorn the place where the grubs have 

 spun their group of silken cocoons in which to pass the 

 winter. 



Generartion of Ichneumons n «, tlie citcipillnr of PonJia Brassica. 

 h, the esgs ot tli it bnttiiH\ filiieii to i It if <, MlcroirMtcr ^lomeintus, 

 magnified. (/ d il, ■\ miijiiiined m< w of i di-sictwi caieipillar, in whose 

 body a numbci o( k hn< union ratei pdlara ha\ e been hatched, c, silk co- 

 coons spun b\ th( itlineuinons A>,iub3 hiunniiig cocoons, f, grubs 

 eating their wa> out ol the caterpilldi 



