Common Insect Enemies 107 



tween the fly and equine populations? Unless you are a 

 member of the younger generation you can remember the 

 days when our city streets were covered with evidence that the 

 horse reigned supreme in the field of transportation. He 

 pulled the milk wagon, the grocer's delivery wagon, and the 

 brewery truck; and the surrey with the fringe on top was a 

 reality instead of a popular song. 



Being uninhibited in their toilet habits, the multitude 

 of horses furnished work for numerous white wings; but it 

 was a losing battle for the pushers of the broom: their task 

 was never finished. This was a paradise for flies : they liked 

 the manure-covered streets, and the manure piles behind every 

 stable furnished ideal breeding places for them. The result: 

 flies, flies, flies! Every time one went into or out of the 

 house, a swarm of flies, lurking around the screen door> made 

 a dash for the cooler interior of the house and the tempting 

 food upon the dining room or kitchen table. 



Who could visualize in the early days of this century 

 that the chugging one-cylinder horseless carriage would some 

 day banish the horse from the city streets, and with it, the fly? 

 Yet, that is what has happened. In our metropolitan areas 

 today, the old gray mare "ain't what she used to be," and the 

 fly is a negligible factor in the transmission of disease. 



In rural regions, however, the fly is still with us in quan- 

 tity, for the tractor has not yet eliminated the horse, and no 

 one has invented a satisfactory substitute for milk or beef- 

 steak. The farmer, however, can now make his premises as 

 free from flies as city streets by simply treating his barns and 

 animals and manure piles with DDT compositions. Just 

 to give you a few examples: In experiments where manure 

 piles were treated with a /4 % DDT solution, no flies subse- 

 quently emerged, and barns sprayed with DDT solution 



