RELATION TO AGRICULTURE 27 



the animal kingdom. To them is due a consider- 

 able amount of disease among domesticated ani- 

 mals. Their rate of reproduction is appalling. 

 Their numbers amount to a figure too enormous 

 for the human mind to grasp. Their appetite 

 is tremendous; in proportion to his size a man 

 to keep on an even basis with some of them would 

 have to consume tons of food at a meal. The 

 flesh-eating larvae of some flies will devour a hun- 

 dred times their own weight of meat in twenty- 

 four hours, and a caterpillar in a day will con- 

 sume a leaf weighing ten times itself. There- 

 fore, insects, unhampered and unhindered, are a 

 serious menace to agriculture in all its forms. 



Fortunately, as outlined in the previous chap- 

 ter, the insects are circumscribed on all sides by 

 limiting factors which serve to maintain their 

 population within moderate bounds. The world 

 is at odds with them in order to keep the Balance, 

 which the coming of cultivation so nearly upset. 



As the agricultural expert has learned to know 

 insects, he separates them into three groups, 

 vegetable-eaters, predaceous forms, and species 

 parasitical to his live stock. The last group are 

 controlled by washing and spraying the domes- 

 ticated animals, but the others survive artificial 

 methods of getting rid of them by poison. 



The vegetable-eaters, as their name implies, 

 include all the species whose food consists of veg- 

 etable matter. These are responsible among 



