HORSE-FLIES AND WESTERN AGRICULTURE. 3 



INJURIOUSNESS AND ABUNDANCE. 



LOSS OF BLOOD. 



The loss of blood sustained by animals attacked by blood-sucking 

 flies is considerable. It is estimated that eight flies of Tabanus 

 phaenops Osten Sacken, or " greenheads," having fully fed upon 

 an animal, take altogether 1 cubic centimeter of blood. T. pvmetifer 

 Osten Sacken, a fly still larger, will take more blood than T.phaenopH. 

 During a season when tabanids are abundant, very commonly as 

 many as 25 to 30 greenheads and 8 to 10 adults of T. punctifer are 

 seen feeding on one cow (fig. 1). Considering that it takes a 

 fly only about eight to ten minutes to complete its meal of blood, 

 and that during one day an average of 25 to 30 flies may feed 

 on the animal for six hours, the loss of blood could amount to 100 

 cubic centimeters in one day. This estimate is conservative. Many 

 isolated animals, horses in harness, and animals too weak to fight 

 the flies vigorously suffer a greater loss in blood than this. 



Fig. 2. — Horses and mules grouped together for mutual protection from horse-fly attack. 



LOSS OF FEED. 



Another way in which the flies cause an important loss is by inter- 

 fering with the feeding of the stock. During the time of day when 

 flies are very abundant, from about 10 a. m. to 5 p. m., the horses 

 and cattle cease feeding and bunch together for the purpose of fight- 

 ing the flies (fig. 2.). In addition to the loss of feed during this 

 bunching of the animals, many wounds result from hooking and 

 kicking, and these become portals of infectious diseases or infesta- 

 tions by fly maggots. J. H. Clemons and W. W. Cunningham, cattle 

 company officials, stated that the flies seriously retarded the fatten- 

 ing of the cattle. 



CAUSE OF RUNAWAYS. 



A considerable loss due to the flies is that from runaways of horses 

 in harness. Mr. Clemons refers to several such accidents resulting in 

 casualties as well as destruction to harness, machinery, and fences. 



CARRIERS OF DISEASE. 



Possibly even more serious than these losses is that due to various 

 diseases transmitted and disseminated among domestic animals by 

 tabanids. 



