80 DAIRY FARMING 



except that its mouth parts enable it to bite while the house 

 fly cannot. The horn fly is a native of Europe and was 

 introduced into this country about 1886. It is recognized 

 from its habit of feeding with wings spread, and it usually 

 travels in swarms. It is also seen at times gathered around 

 the base of the horn. 



Many of the flies that annoy cattle are hatched in manure. 

 The first precaution to be observed, in any attempt to re- 

 duce the number, is to avoid an accumulation of manure where 

 it will remain moist, especially near the barn. Horse manure 

 is preferred by these pests, but they breed in any, even that 

 dropped in the fields by the animals. No practical method 

 has been devised that will do more than reduce the number 

 of flies very slightly. Large fly traps in the barn have been 

 used with some success. Screens on the barn are generally 

 found worse than useless since the flies accompany the 

 animals into the barn and then remain in the barn if the win- 

 dows are screened. 



Milk rooms should always be protected by screens, on 

 account of the serious danger of flies carrying germs of 

 human diseases into the milk. 



In recent years a great many preparations designed to 

 repel flies have been placed on the market. These fly re- 

 pellents consist chiefly of some coal tar products with the 

 addition of fish oil, resin, or pine tar. Results at three 

 experiment stations go to show that there is little value in 

 using these preparations. If they are applied daily, it is pos- 

 sible to keep the flies away fairly well, but it is questionable 

 whether the animal does not suffer more from having the 

 pores of its skin closed up with the oily substance than it 

 does from the insect. There is no appreciable increase in the 

 milk flow when these substances are used. 



