CHAPTER X 
THe NaruraL Enemies oF INsects 
TuHar insects have a host of natural enemies which constantly prey on 
them is as certain as the fact that insects exist at all. [fit 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 preéminently 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. 
Fic. 45. — Protective resem- 
Fic. 44.— Protective coloration. Butterflies blance. Moth on the trunk 
among dead leaves. Original. of atree. 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. 
4o 
