^80 



fiENEPICIAL INSECTS, 



the foes escape but they in turu are checked till all species can live and 

 fill their place in the natural world, the balance of life evenly kept between 

 the herbivores, the scavengers, the parasites and predators. In this 

 connection we may mention the birds, which do so much to keep the 



Fig. 346. 

 A Fraying Mantis. 



balance even by snapping- up all insects that become abundant ; an insect 

 that escapes its foes and outruns its parasites is apt to fall a victim to 

 birds as do the termites when they emerge in swarms ; if not to a bird, 

 then to a lizard, a toad or a bat. All these are useful and all should be 

 encouraged. A large number of birds are wholly insectivorous, a large 

 number are partly so, and every one of these deserves protection and 

 encouragement. They fill an extraordinary place in nature as they 

 move from place to place, they are nearly omnivorous insect-eaters 

 and they snatch up the floating balance of insect life, acting as a 

 kind of safety-valve. For the birds we should plant trees, which rarely 

 harbour crop pests, and especially such trees as figs on which the mynas 

 ffather and feed. 



