12 THE HOUSE FLY— DISEASE CARRIER 



foul with excremental products, if they were kept moist 

 and at a suitable temperature. He also reared adult 

 flies from decaying vegetables thrown away as kitchen 

 refuse, and on such fruits as bananas, apricots, cherries, 

 plums, and peaches, which were mixed when in a rot- 

 ting condition with earth to make a more solid mass. 

 He succeeded in rearing them in bread soaked in milk 

 and boiled egg and kept at a temperature of 25° C, 

 but he was unable to rear them to maturity in cheese. 

 The preference which the typhoid fly has for horse 

 manure as a breeding nidus has been clearly shown 

 by a multitude of observations. One of the early ex- 

 periences of the writer consisted in an effort to keep 

 the stables of the U. S. Department of Agriculture at 

 Washington in a strictly sanitary condition. The ma- 

 nure was swept up and placed each day in a screened 

 closet. As a result there was a notable diminution of 

 flies in all of the buildings for hundreds of yards 

 around for several weeks; whereas up to the time when 

 the experiment began they had been a nuisance through- 

 out that portion of the city. One of the many letters 

 received which bear upon this point may be quoted : 



Washington, D. C, February 10, 1908. 

 "Dr. L. O. Howard, 



Department of Agriculture, 

 IVashington, D. C. 

 "Dear Dr. Howard: 



"For the greater part of the last two years I have oc- 

 cupied a room on the third floor of the Faculty Club on 

 the Campus of the University of California at Berkeley, 

 Calif. During most of the time the number of flies in 



