CHAPTER X 



The Natural Enemies of Insects 



That insects have a host of natural enemies which constantly prey on 

 them is as certain as the fact that insects exist at all. If it were not so, 

 and if our pests reached the full limit of their powers of increase un- 

 checked, there would shortly be no living plant left on the face of the 

 earth, and no trace of animal life. Insects possess preeminently, the 

 ability to multiply rapidly and to spread widely. Thus it has been 

 computed that the progeny of one plant louse in a single season, if 

 allowed to multiply at the maximum rate and if none suffered accidental 

 death, would make a mass of matter equal in weight to that of the 

 earth. 



Fig. 44. — Protective coloration. Butterflies 

 among dead leaves. Original. 



Fig. 45. — Protective resem- 

 blance. Moth on the trunk 

 of a tree. Original. 



Birds and Other Animals 



Among the higher animals that destroy noxious insects birds are 

 entitled undoubtedly to first rank. Few of us appreciate their services. 



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