408 THE MANAGEMENT AND FEEDING OF CATTLE 



negative results. They succeeded in protecting the 

 cows more or less completely from flies, but got no in- 

 crease virtually in the milk yields. In view of these 

 results, the conclusion is irresistible that unrest from 

 this source does not act similarly to unrest from other 

 sources. It may be true, however, that, viewed from 

 the standpoint of production, it may not pay to use 

 repellents in the effort to protect cattle from the com- 

 mon house fly. 



The protective measures that have been used against 

 flies include the following: (i) Darkening the stables 

 provided with proper openings and screens for ventila- 

 tion; (2) contrivances for catching flies or brushing them 

 off as they enter the stables; (3) the application of cer- 

 tain powders, as tobacco, to destro}' them, and (4) the 

 application of repellents, as 10 to 15 per cent kerosene 

 and water, kept properly agitated, fish oil with 3 per 

 cent of carbolic acid and kerosene emulsion, also pro- 

 prietary remedies of which there are many in the mar- 

 ket. The repellents are applied with sponge, brush, or 

 spray, according to the nature of the material and the 

 number of animals to be treated. It would seem correct 

 to say that of the above, a properly darkened basement 

 stable to which the animals are given access during the 

 warmer portion of the day is the most effective protec- 

 tion against common flies that can be devised. It will 

 not protect equally against the horn fly, the annoyance 

 from which goes on by night as well as by day. The 

 common fly is more active by far in the light. But such 

 protection will not increase production unless the ven- 

 tilation secures more coolness than is obtainable outside. 

 Screens made from material used in making sacks, with 

 or without wire screens underneath, may sufficiently 

 exclude the light. More coolness may be obtained in a 

 basement ordinarily that rests against a bank than in 

 one that does not. 



