Vol. XXXII, No. 1 



WASHINGTON 



July, 1917 



THE RAT PEST 



The Labor of 200,000 Men in the United States Required 



to Support Rats, Man's Most Destructive 



and Dangerous Enemy 



By Edward W. Nelson 

 Chief oe the U. S. Biologicae Survey. 



Readers of the Geographic will recall with pleasure Mr. Nelson's informative 

 article on the Larger North American Mammals, published in this magazine in 

 November, 1916, and illustrated by a remarkable series of four-color reproductions 

 of paintings by Louis Agassis Fuertes. The following article embraces informa- 

 tion obtained by Mr. Nelson during years of research and study of mammals, 

 especially rats and squirrels. A third article by this author zvill be published in 

 an early issue of the Geographic, his subject being the Smaller North American 

 Mammals, illustrated by a second series of 32 pages of color illustrations repro- 

 duced from Mr. Fuertes' paintings. 



H 



OUSE rats are extremely nu- 

 merous and are world-wide in 

 distribution. At the present time 

 they destroy annually hundreds of mil- 

 lions of dollars' worth of foodstuffs and 

 other property, and through the distribu- 

 tion of bubonic plague and other diseases 

 cause the deaths of untold numbers of 

 human beings. These facts being known, 

 why should we delay in vigorously using 

 known methods for the elimination from 

 our homes and communities of these 

 wasteful and loathsome pests? 



The common house - frequenting rats 

 are of three species, the brown, the black, 

 and the roof rat. All are believed to be 

 natives of Asia, whence they have spread 

 to most parts of the world. In their re- 

 lations to man their habits are so similar 

 that they may be included in one account. 

 The larger size, abundance, more general 

 distribution, and aggressive predominance 



of the brown rat, also known as the Nor- 

 way and wharf rat, has led to its being 

 generally known as "the house rat." 



So far as known, these rodents are 

 always and everywhere thoroughgoing 

 pests, with no usefulness to man. 



The history of the brown rat is an ex- 

 traordinary one, unequaled by that of any 

 other mammal. It was unknown in Eu- 

 rope until 1727, when vast hordes of 

 them swam the Volga River. A year or 

 two later it arrived in England on ships 

 from the Orient. Since that time it has 

 steadily extended its distribution by 

 means of ships and other transportation 

 agencies, and by migrations overland, 

 until it shares with mankind nearly all 

 parts of the earth from Greenland to 

 Patagonia and around the globe. 



It is a sturdy, fierce, and cunning ani- 

 mal with extraordinary fecundity. These 

 characteristics have enabled it quickly to 



