148 The Field Naturalist's Quarterly May 



Ichneumons. 



By Claude Morley, F.E.S., &c. 



Amongst the handsomest and most interesting insects 

 which will force themselves upon your observation during 

 a country stroll in any of the summer months are the 

 parasitic flies known as Ichneumons. They are so abundant 

 that to drag the sweep-net over the herbage, or to swing the 

 butterfly -net through the air on any windless day, is to 

 capture several of them ; and when one contemplates that 

 each of these organisms has attained maturity at the expense 

 of another's life, one is led to wonder wherein this life is 

 better or more beneficial than that which has been sacrificed 

 to its birth. " There is nothing fixed in Nature ; " yet is her 

 stability great ! Though the course of evolution is constantly 

 progressing, the progress must be for the benefit of Nature 

 as a whole at the expense of any particular group. The 

 caterpillars of the majority of insects are extremely injurious 

 to the vegetable kingdom : they not only defoliate the trees 

 and shrubs, demolish the herbage to its roots, and ruin our 

 food-stuffs, but the very inner wood of great trees and the 

 roots of the plants are attacked by certain kinds. Were 

 these ravishers to have full sway we should very quickly 

 have, for instance, no cabbages for dinner, no corn for our 

 bread, no flowers for our vases, and, above all, the landscape 

 would be devoid of the lovely leaves, grasses, and plants 

 that are now so pleasing and restful to the eye, presenting 

 but a sere and barren waste. That so great a calamity does 

 not occur any day is due to the pertinacity of the cater- 

 pillars' enemies, among which none is more fell than the 

 Ichneumon, whose duty it is to search out the pests in their 

 own proper retreats and there to slay them, not swiftly and 

 directly, but slowly and insidiously, though none the less 

 surely. 



An egg is inserted by the Ichneumon beneath or upon the 

 caterpillar's skin, which, when hatched into a footless grub, 

 begins to assimilate to its own body the juices stored in the 



