LETTER OF TRANSMITTAL. 
U. 8. DEPARTMENT OF AGRICULTURE, 
Division oF ENTOMOLOGY, 
Washington, D. C., July 24, 1900. 
Str: 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 the 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. Howarp, 
Lintomologist. 
Hon. JAMES Witson, 
Secretary of Agriculture. 
