rilAPTER XVII 



THE KAT PROBLEM 



The rat is the worst nuiuiinaliaii pest known to man. Its depredations 

 throughout the world result in losses amounting to hundreds of millions of 

 dollars annually. But these losses, great as they are, are of less importanc«' 

 than the fact that rats carry from house to house and from seaport to sea- 

 port the germs of the dreaded plague. — David Lantz, "The Brown Bat 

 in the United States," p. 9. Bulletin No. 33, Biological Survey, United States 

 Department of Agriculture 



The smell of mice shall be in their nostrils and they shall die. — Old myiufj 



To pay $1,000,000 for the last pair of rats on the North 

 American continent, after the Panama ('anal is cut through, 

 and every harbor is properly sea-walled, might be money well 

 expended. The warfare which has been going on for thou- 

 sands of years mioht then be terminated in at least one conti- 

 nent — and may not all good Americans unite hi the hope 

 that ours may be the first conthient of wliich this is true ? 



The failure of all attempts to deal witli tliis vile enemy 

 may be traceable to lack of a vivid realization of what the 

 '' last pair " may do in the way of increase. The brown rat 

 may breed five times in a season and have from 6 to 23 young 

 at a litter. Allowing 8 young, the iiu-rease from a single pair 

 in a season may amount to 880 ; and if we liguri' 10 in a \\\{v\\ 

 this number is hicreased to 1250. In three years with only (J 

 young in a litter Lantz has computed the possible hicrease at 

 20,155,392. From these data it is clear that any scientific 

 method of dealinu' with this pi-oblcm in any home or loijditv 

 must catch the last pair, and also, under existing conditions, 

 insure catching the first pair as soon as ii comes. 



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