THE RAT AS AN ECONOMIC FACTOR. 



By DAVID E. LANTZ, 



Assistant Biologist, United States Department of Agriculture. 



INTRODUCTION. 



The world has rightly learned to dread rats as disseminators of 

 disease, and recent efforts to rid cities of the pests have resulted 

 chiefly from sanitary considerations. Yet the material losses due to 

 depredations of rats are now, and always have been, a sufficient argu- 

 ment for their destruction. The requirements of sanitation and 

 public health are slowly bringing to pass what economic interests 

 failed to accomplish, namely, a general recognition of the fact that 

 the rat is a standing menace to prosperity. To point out some of 

 the many ways in which rats inflict injury and the extent to which 

 they drain the resources of the people is the object of the present 

 chapter. 



UTILITY OF THE RAT. 



Do rats serve any useful purpose? With very slight reservation, 

 the question may be answered in the negative. There have been 

 times and places in which the rat's work as a scavenger accomplished 

 good, but modern methods of garbage disposal are superseding the 

 feeding it to rats. 



It was Robert Southey, the poet, who, nearly a century ago, 

 humorously suggested as the first three steps to eradicate rats first, 

 introducing them as a table delicacy; second, utilizing the skins; and 

 third, inoculating them with a contagious disease. The last of these 

 plans is now receiving considerable attention from bacteriologists, but 

 the others, for obvious reasons, have been neglected. 



It is true that under exceptional circumstances the rat has been a 

 source of human food. The principal instances on record were during 

 the siege of Paris in 1870, and during the siege of the French garrison 

 at Malta, 1 798-1800, when food was so scarce that rat carcasses brought 

 high prices. Another was on board the ship Advance during an 



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