90 LONDON INSECTS 



which it either actually bores into trees or pokes 

 through cracks till it finds the soft body of an unsus- 

 pecting Caterpillar, into which an egg is slipped, to 

 hatch in good time and eat its unwilling foster-mother. 

 There are numberless varieties of the kind, many of 

 which are believed only to lay their eggs in particular 

 larvae. The poor old Daddy Longlegs have the 

 questionable honour of an Ichneumon-fly, which seems 

 to confine its attention mainly, if not entirely, to 

 them. ' It is impossible/ writes Mr. Wood in his little 

 book on Common British Moths, 'to detect a stung 

 Caterpillar till it has ceased feeding, and not always 

 easy to detect it even at that time. Often the Cater- 

 pillar 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 collector finds that instead of the Moth 

 the Ichneumon-fly occupies the box.' It is satis- 

 factory to know, on the authority of Professor Duncan, 

 that a poetic justice occasionally reaches some, at 

 least, of the murderers. 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 



