170 A COLLECTOR'S EXPERIENCES 



tiles explains their use in the economy of Nature. 

 Many species of snakes, among them the larger 

 constrictors of the Sputhem States, are found more 

 abundantly in fields of growing corn or sugar-cane 

 than in any other location. During the spring, when 

 these fields are furrowed, these reptiles are cast from 

 their hiding-places by the plow, showing their aver- 

 sion against leaving the fields even for the period of 

 hibernation. Their presence there is easily explained. 

 Coming from the near-by woods are rodents and other 

 small creatures that collect in these fields to feed upon 

 the products of tilled soil. Unmolested, their ravages 

 would be disastrous; but Nature has carefully laid 

 her plans to check their multiplication. A single 

 blacksnake, during the summer months, will devour 

 dozens upon dozens of mice, will prowl through the 

 burrows of shrews and moles, devour the young, and 

 go in searcji of more. The appearance of a black- 

 snake in a field of grain guarantees the destruction 

 of many of the farmer's most elusive enemies. 



Although a great many reptiles play havoc among 

 the smaller mammals, there are other species which 

 confine their attention to the regulation in numbers 

 of their own class. These are cannibals, and feed 

 almost exclusively upon snakes and lizards. Many 

 of the cannibal snakes are gifted with an immunity 

 against the poison of the venomous species, which 

 they attack and devour. 



Burrowing in the pulp of decaying trees and 

 searching in the bark of the living, are forms of rep- 

 tile life but seldom seen by the eyes of the uniniti- 



