, INSECTS BENEFICIAL AND BEAUTIFUL 247 



I was watching, hunt over the surface inch by inch for 

 a likely place to drill ; but, after about an hour's search, 

 she flew away. Certainly nothing I have ever observed 

 has so impressed upon my mind the marvelous perfection 

 of Nature's mechanisms and the completeness with which 

 every darkest nook and corner of her domain is guarded. 

 A horntail, Tremex, bores deep into the tree and deposits 

 her egg. Who would think that any harm could reach it 

 there ? But the ichneumon fly is armed and equipped for 



Fig. 102. Black Thalessa 

 d, drill ; ov, ovipositor. (I'o natural size) 



her task. Her egg hatches in the burrow of the Tremex, 

 the young ichneumon finds the wood-boring larva, lives as 

 a parasite upon it, and, finally, after completing its trans- 

 formations, emerges as the ichneumon fly in the picture. 



There are more than a thousand genera of ichneumon 

 flies, with, of course, a great many more species, and if 

 the Tremex larva is not safe in the heart of a maple tree, 

 what must be the fate of the thousands of larvae that feed 



