3i8 BIOLOGY AND HUMAN LIFE 



restaurants, or picnic grounds. Flies will visit open wounds or 

 sores on the bodies of animals, and they will visit the excrements 

 of man and other animals; and then they will regurgitate, or 

 cast back, the contents of the crop upon some dry food, like 

 sugar, thus transferring some of their earlier intake. We can 

 see, then, what excellent opportunities this animal has not only 

 to collect a varied assortment of bacteria but also to distribute 

 them widely. 



From a report made by an army commission as to the causes of epi- 

 demic fevers in the army camps during the Spanish-American War we 

 learn that "flies swarmed over infected fecal matter in the pits and fed 

 upon the food prepared for the soldiers in the mess tents. In some in- 

 stances where lime had recently been sprinkled over the contents of the 

 pits, flies with their feet whitened with lime were seen walking over the 

 food." We can readily understand why it was that more soldiers were 

 killed by intestinal diseases than by Spanish bullets. 



243. Fighting flies. Just as soon as we realize the relations 

 of the house fly to mankind we are tempted to ''swat" every fly 

 we see; but if we all swatted flies, and did only that, the fly 

 pest would hardly receive a serious check, for the insect breeds 

 faster than you and I can kill the progeny, and there is nothing 

 to prevent the flies raised in the stable down the street from 

 coming into our yard. 



We have to attack the insects before they are old enough to 

 fly about ; that is, we must prevent their breeding by removing, 

 destroying, screening thoroughly, or poisoning all materials that 

 may serve as food for the maggots. The struggle between man 

 and the fly is not that of a particular person against a particular 

 fly, but of one species against another, and we must carry on our 

 end of the fight through community or group action. Better 

 than swatting the fly is the complete elimination of the tribe 

 from all places inhabited by human beings. 



On the farm or in a village stable manure can be profitably 

 spread out upon the ground, in field or garden, every day or 

 two. The manure will then dry quickly and the sunlight will 

 kill eggs and maggots. In larger towns and cities it should not 



