226 THE ECONOMIC IMPORTANCE OF ANIMALS 



the various state experiment stations, and medical and civic 

 organizations. 



The Bureau of Entomology works in harmony with the other 

 divisions of the Department of Agriculture, giving the time of its 

 experts to the problems of controlling insects which, for good or 

 ill, influence man's welfare in this country. The destruction of 

 the malarial mosquito and control of the typHoid fly ; the de- 

 struction of harmful insects by the introduction of their natural 

 enemies, plant or animal ; the perfecting of the honeybee (see 

 Hodge, Nature Study and Life, page 240), and the introduction of 

 new species of insects to pollinate flowers not native to this country 

 (see Blastophaga, page 43), are some of the problems to which these 

 men are now devoting their time. 



All the states and territories have, since 1888, established state 

 experiment stations, which work in cooperation with the govern- 

 ment in the war .upon injurious insects. These stations are often 

 connected with colleges, so that young men who are interested in 

 this kind of natural science may have opportunity to learn and to 

 help. 



The good done by these means directly and indirectly is very 

 great. Bulletins are published by the various state stations and 

 by the Department of Agriculture, most of which may be obtained 

 free. The most interesting of these from the high school stand- 

 point are the Farmers' Bulletins, issued by 

 the Department of Agriculture, and the 

 Nature Study pamphlets issued by the 

 Cornell University in New York state. 



Animals Other than Insects may be Dis- 

 ease Carriers. The common brown rat is 

 an example of a mammal, harmful to civi- 

 lized man, which has followed in his foot- 



This diagram shows how ste P s a11 over the world - Starting from 



bubonic plague is carried China, it spread to eastern Europe, thence 



diagram'. ' to western Europe, and in 1775 it had 



obtained a lodgment in this country. In 



seventy-five years it reached the Pacific coast, and is now fairly 

 common all over the United States, being one of the most prolific 



