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CHAPTER X. 

 Insects and their Natural Enemies. 



Insects, in the present age, may be said to be the 

 dominant animals of the world. Not only do they greatly 

 exceed all other classes of the animal kingdom in point of 

 numbers of species, but many of these species occur in most 

 amazing abundance. 



Like all other living creatures, they form part of 

 a complex scheme in nature made up of relationships 

 between these forms. The relationship of insects to plants 

 is generally that of an animal to its food ; that is to say, 

 insects for the most part are plant feeders, and when 

 this relationship exists between an insect which occurs 

 in considerable numbers, and plants which are of use to 

 man, the insect is generally considered a pest. Some 

 insects also procure their food by sucking the blood, or 

 devouring the tissues, of animals. These may be parasitic 

 or predaceous. Other insects, still, derive their sustenance 

 from dead or deca3'ing organic substances, and are known 

 as scavengers. 



Insects also serve as food for other insects, for birds, 

 toads and lizards ; these are called their natural enemies, 

 and there are also certain forms of plant life which are 

 able to attack and kill living insects, which are also to be 

 included among their natural enemies. It will thus be seen 

 that insects play a considerable part in the relationships 

 which exist in the plan of nature. If it were not for the 

 effect of natural enemies on insects, the world would in 

 a short time become absolutely uninhabitable to any other 

 forms of life, except perhaps the very lowest plants and 

 animals, and the insects themselves would shortly die off, 

 killed by starvation. 



The natural enemies of insects may be considered under 

 the following heads : 



