REPELLENTS FOR PROTECTING ANIMALS FROM FLIES. 3 



which flies occur, the irritation they cause animals, the blood they 

 abstract, the movements they cause animals to make in fighting them, 

 and the unfavorable influence they have on the temper of dairy cows, 

 it is believed by both scientist and layman that flies are responsible 

 for very great financial losses. 



According to Delamare (1908), a German professor named Leh- 

 mann is stated to have established that the supplementary expendi- 

 ture of energy corresponding to the agitation caused horses by the 

 attacks of flies amounts to a pound of oats a head per day. Moore 

 (1903), of the South Dakota Agricultural Experiment Station, says: 

 "When we consider the intimate relationship existing between the 

 milk yield and the physical comfort of the cow, no question can be 

 raised as to the benefit obtained by mitigating so far as possible the 

 annoyances of these pests." Hopkins (1891) states that the hornfly 

 so annoys cattle by its bite that the cows fail in milk and other cattle 

 fail in flesh. Garman (1892) says: "The injury done to cattle has 

 been greatly overestimated in some instances; yet there can be no 

 doubt that the yield of milk from cows greatly worried by hornflies is 

 much reduced, and growing and fattening stock are doubtless re- 

 tarded by their attacks." Marlatt (1910) states: "During the first 

 years of the hornfly, when it was a new and little understood menace 

 to cattle, the losses occasioned by it were undoubtedly much exagger- 

 ated. Nevertheless, the loss when the fly is abundant is still very 

 considerable, showing in reduced vitality, lack of growth, or less- 

 ened yield of milk, the production of milk often being cut down 

 from one-fourth to one-half. In Canada the late Dr. James Fletcher 

 estimated the loss in Ontario and Quebec at one-half the product of 

 meat and milk." Bishopp (1913) describes an unusual outbreak of 

 the stable fly in 1912 in northern Texas and refers to various other 

 outbreaks that have occurred in the United States. In referring to 

 the injury due to the fly he states that many horses and cattle became 

 so weak that they gave up the fight against the pest. In a few cases 

 in which the animals were not protected they succumbed in a short time. 

 Texas fever was rekindled in an acute form in cattle that became 

 weakened as a result of the flies, and in many cases death resulted. 

 The influence of the flies on the milk production was marked, the 

 reduction being from 40 to 60 per cent, and in some cases cows were 

 completely dried up. Horses and mules lost 10 to 15 per cent in 

 weight during the outbreak. Cattle likewise suffered a great reduc- 

 tion in weight. It is estimated that in northern Texas over 300 head 

 of cattle, mules, and horses were killed directly or indirectly as the 

 result of the fly attack. This loss is estimated at $15,000, and the loss 

 in the milk production is placed at $10,000, and other losses are stated 

 to surpass these. 



