Prevention and treatment of the disorders caused by 
horse bots concern thousands of horse owners in this 
country. In 1970, the total horse population in the United 
States was approximately 7,000,000 animals. Of this num- 
ber, about 2,739,500 were farm horses and mules; and 
about 4,260,500 were nonfarm or light horses. 
Although the number of draft animals has declined 
steadily since the advent of the tractor, maintaining the 
health of draft animals still in use is vital in many areas. 
And the increasing popularity of light horses has created 
new demands for information about horse health, 
To meet the needs of horsemen for help in controlling 
horse bots, the U.S. Department of Agriculture publishes 
this leaflet. 
This edition replaces all previous editions of this publication. Because of changed 
insecticide recommendations, earlier copies should be destroyed. 
