LETT1:R OF TRANSMITTAL. 



IT. S. Department of Agriculture, 



DiYisioN OF Entomology. 



Was/dngton, D. C. , July ^If., 1900. 

 Sir: I have the honor to transmit herewith manuscript of a bulletin 

 on the mosquitoes of the United States, which gives some account of 

 their structure and biology and indicates thg differences in all stages 

 of existence between the kinds of mosquitoes which have been shown 

 to transmit malaria and those which do not. It also treats of the sub- 

 ject of remedies in considerable detail. It has been written mainly 

 from the popular standpoint, although scientific details of structure 

 and classification have been inserted for the use of physicians engaged 

 in studying malaria. I recommend that it be published as Bulletin No. 

 25, New Series. 



Respectfully, L. O. Howard, 



Entomologist. 

 Hon. James Wilson, 



Secretary of Agriculttire, 



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