148 London Insects. 



even at that time. Often the Caterpillar changes into 

 a chrysalis without betraying any signs of the mortal 

 injury it has sustained, but when the time arrives for 

 the appearance of the insect, the disappointed col- 

 lector finds that instead of the Moth the Ichneumon 

 Fly occupies the box." It is satisfactory to know, 

 on the authority of Professor Duncan, that a poetic 

 justice occasionally reaches some, at least, of the mur- 

 derers. Sometimes the springy ovi-positor, when 

 pressed against the tree, glances from it, and shoots 

 the egg into the last place the mother had intended 

 her own body and she flies off to become a 

 living presentment of Milton's image of Sin at 

 Hell's gate, with her children gnawing night and 

 day at her vitals. 



Marvels of contrivance meet us at every turn of the 

 page in Natural History. 



Knowing the ordinary conditions of feeding-life of 

 almost every kind, one would have supposed it im- 

 possible that an animal should live for many days 

 with another creature of comparatively large size 

 living and eating in its tissues, without dying of 

 blood-poisoning, or whatever else may be its equiva- 

 lent in an insect. 



But this danger is avoided by a most strange 

 peculiarity of construction which is found in the 

 larvae of such parasitical Flies and of Bees. If any- 

 one wishes to know how it is that a beehive is sweet, 

 in spite of the crowds of hungry Grubs crammed into 

 it, or why the juices of a Caterpillar attacked by an 

 Ichneumon are not fatally tainted, he may read a 

 reason in No. XVI 1 1.* of Professor Owen's Lectures 

 on " Invertebrate Anatomy." 



In England, if a Caterpillar or Grub escapes the 

 * See Appendix C. 



