216 DAIRY CATTLE AND MILK PRODUCTION 



sometimes kept in a screened inclosure. When the weather 

 is damp so the manure dropped in the field remains moist a 

 sufficient length of time, the flies hatch freely wherever drop- 

 pings are found. In dry seasons this opportunity does not 

 occur, and the number of flies is usually much smaller. 



The popular idea of the great injury done by flies has re- 

 sulted in many proprietary mixtures being put on the market 

 designed for the purpose of keeping off the flies. The com- 

 pounds are usually composed chiefly of some coal tar product 

 with the addition of fish oil, resin, or pine tar. These are ap- 

 plied to the animal with a hand spray pump. Great claims 

 are made by the manufacturers regarding the injury done by 

 flies and the profit resulting from using these repellents. In- 

 vestigations made by at least three experiment stations have 

 failed to show any advantages from their use. 



Lindsay l reports trials with ten brands of fly removers. 

 Four of these he found were efficient in keeping off the flies, 

 the others were not. He did not determine the effect on the 

 milk and butter production of the cows. 



Beach and Clark 2 report an extensive trial to determine 

 the effect of applying one of these preparations on the milk 

 and butter fat yield of cows. The trial covered two summers. 

 They concluded that while the preparation they used pro- 

 tected the cows fairly well against the flies, the milk and fat 

 production was not increased when the cows were sprayed. 

 Their investigation indicates that the annoyance of cows by 

 flies is overestimated. 



The author 3 carried on a similar trial during the summers of 



1 Fifteenth Annual Report, Mass. Experiment Station. 

 1 Bulletin 32, Storrs Experiment Station, Storrs, Conn. 

 8 Bulletin 68, Missouri Experiment Station. 



