February, '17] ENTOMOLOGISTS' DISCUSSIONS 113 



though there was considerable protection afforded for two and even 

 three d^ys. To accord full protection, the cows should be sprayed 

 each day. 



In the third phase, the comparative value of morning and afternoon 

 applications was tested. The cows were sprayed between 3 and 4 

 a. m. prior to milking, and were then turned out to graze. Observa- 

 tions in the field during this period showed the cows to be very little 

 troubled by flies, and grazing or resting quietly. When they came in 

 to be milked, there were few flies on the animals. The cows were 

 quiet during the milking and did not exhibit the extreme nervousness 

 displayed prior to the spraying. 



The fourth test consisted of taking the records of the herd, half of 

 which was sprayed once a day in the morning, with 3 per cent emulsion, 

 and the balance left unsprayed. These notes are of a preliminary 

 nature, and afford a possible index of what may be expected. The 

 future tests will be on farrow cows, so maintained for a sufficient period 

 to yield results. The indications from the preliminary records are 

 that an increased average yield should result from protection from 

 flies. Such an increase was obtained in this test. 



The cost of the spraying was less than one-half cent per cow per 

 application. 



President C. Gordon Hewitt: This paper is open for discussion. 



Mr. T. J. Headlee: Are there any figures on the increased yield of 

 milk? The treatment costs half a cent a day per cow. What is the 

 benefit? 



Mr. E. N. Cory: We know that our results are open to several 

 experimental errors. The cows selected were hardly a representative 

 lot, and yet comparing the record of the ten days prior to spraying 

 with the ten days during the spraying period, we found there was an 

 average increase of three pounds of milk per animal. The work next 

 year will be continued over a longer period and we hope to get more 

 definite figures on milk production. 



Mr. R. a. Cooley: What were the species of flies concerned? 



Mr. E. N. Cory: The principal flies were the horn-fly, Hcematohia 

 serrata and the stable fly, Stomoxys calciirans. 



President C. Gordon Hewitt: The point raised by Doctor 

 Headlee is an important one in connection with all these experiments 

 on insects affecting cattle. Everyone knows how difficult it is to con- 

 vince the farmer to undertake any very unusual measures for control 

 of insects affecting his cattle, and he has to be convinced and convinced 

 very strongly that good results will follow. Unless you have actual 

 figures in regard to the effect of the flies on the cattle, without repel- 



