HOW TO DESTROY RATS. 



INTRODUCTION. 



The brown or Norway rat {Mvs norvegicus) is the worst mammal 

 pest in the Unite'd States, the losses from its depredations amonnting 

 to many millions of dollars yearly — to more, probabl}^, than the 

 losses from all other injurious mammals combined.'^ In addition to 

 its destructive habits, this rat is noAv known to be an active agent in 

 disseminating infectious diseases, a fact which renders measures for 

 its destruction doubly important. 



Fig. 1. — Brown rut. 



Introduced into America about 1775, the brown rat has supplanted 

 and nearly exterminated its less robust relative, the black rat, and 

 despite the incessant warfare of man has extended its range and 

 steadily increased in numbers. Its dominance is due to its great 

 fecundity and its ability to adapt itself to all sorts of conditions. It 



^ Several species of rats are known as house rats, including the black rat 

 {Mus rattus), the roof rat {Mus alexandr'mus) , and the brown rat {Mus norve- 

 gicus). Of these, the last is the commonest and most widespread in this coun- 

 try. Not one of these species is a native, but all were imported from the Old 

 World. As their habits in general are similar, the instructions given in the 

 bulletin apply alike to all. 

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