THE FLIES 43 



their full period depending upon season and latitude. During the time 

 of their activity they are a veritable pest to cattle, causing interference 

 with their grazing and disturbance of their rest, with consequent un- 

 thrift and serious loss in productiveness. Horses do not escape their 

 annoyance, but cattle seem to be the special object of their attack. 

 Though the damage done is chiefly through their torment, the con- 

 siderable amount of blood extracted from the animal by the large 

 swarms which feed upon it must seriously contribute to the weakening 

 effects. Further, as in all blood-sucking Diptera visiting cattle, we are 

 justified in inferring that this fly may be a transmitter of infectious blood 

 diseases, such as anthrax, though as to this there has as yet been little 

 if any investigation. 



Control. — In control measures two lines of procedure should be fol- 

 lowed, one looking to prevention of multiplication, the other directly 

 protecting cattle from attack. Of these the former is most effective and 

 involves such treatment of breeding places as will prevent larval develop- 

 ment. As eggs are deposited in fresh dung, which must remain moist for 

 the proper nourishment of the hatched larvae, any treatment of the 

 droppings which will cause them to rapidly dry out will prevent or 

 greatly inhibit larval development. Scattering or thinly spreading this 

 manure, as may be done by a rake or by drawing brush across the fields, 

 will accomplish this; the latter method, more economical in time and 

 labor, is best adapted for large pasture areas. Hogs running with cattle 

 will serve to scatter the manure to a large extent. The use of lime, which 

 may be applied by simply throwing it over the droppings in the pasture, 

 is very effective in destroying the larvae. While piles of cow manure, 

 especially those containing considerable straw, afford good breeding 

 places for the stable fly, the horn fly will not seek this material to any 

 great extent for the deposition of its eggs. 



Protection. — For the direct protection of cattle a number of oleagin- 

 nous repellents are recommended. A mixture of fish oil and tar, equal 

 parts, apphed to the regions most attacked, is one in general use. Almost 

 any oily or greasy substance is of value, though causing the animal to 

 become somewhat unsightly from adhering collections of dust and dirt. 

 Sprays of kerosene emulsion (page 48) may be used with advantage, 

 though the effectiveness of such treatment is very transient. The 

 following mixture is recommended by the Kansas Experiment Station : 

 resin (pulverized), one part; shaved soap, one part; water, one-half part; 

 fish oil, one part; oil of tar, one part; kerosene, one part; water, three 

 parts. The resin, soap, fish oil, and one-half part water are boiled to- 

 gether until the resin is dissolved, then the three parts water are added, 

 and finally the kerosene and oil of tar. The mixture should be thor- 

 oughly stirred and boiled for fifteen minutes. This preparation when 

 cool and applied as a spray will act as an effective repellent for twenty- 



