THE ANIMAL PARASITES OF CATTLE. 497 



"When resting, their wings are held down close to the body (fig. 3); 

 when feeding, their wings are held out nearly at right angles ready 

 for flight. They puncture the skin and suck blood, usually attacking 

 the upper parts of the body, particularly those parts which are out 

 of reach of the animal's head or tail. Unlike most flies, they remain 

 on the animal more or less constantly day and night. Due probably 

 to the irritation and annoyance caused by these flies, cattle often do 

 not thrive as they should during seasons when hornflies are numerous. 

 The hornfly has also been charged with transmitting diseases, such 

 as anthrax. 



The fly lays its eggs in freshly dropped cow manure. They hatch 

 in about twenty-four hours, and the larvse or maggots in four or five 

 days develop to the pupal stage, which lasts a week or ten days. 

 From the pupal stage the mature fly emerges. The entire process of 

 development from the deposition of the egg to the appearance of the 

 mature fly therefore requires on an average about two weeks. To 



Fio. 4.— Hornflies (Hamalobia eerrata) on cow horn. (From Bureau of Entomology.) 



protect cattle from the attacks of the hornfly they may be treated 

 with one of the remedies mentioned above (p. 495). Scattering the 

 droppings of cattle with a shovel, or with brush dragged over pastures, 

 in order to insure the rapid drying of the manure and consequent 

 destruction of the^arvse, is, when practicable, an efficient means of 

 reducing the number of these flies. 



Buffalo Gnats. 

 These small flies, also known as black flies, are about one-eighth of 

 an inch long and have a characteristic "humped" back (fig. 5). 

 They breed in running water and appear in swarms during spring 

 and summer, often in enormous numbers, causing great annoyance to 

 stock and human beings, on account of their bites and their entrance 

 into the eyes, nose, mouth, and other openings of the body. Their 

 bites appear to be poisonous and in seasons especially favorable to 

 the gnats heavy losses of horses and cattle often occur. 

 61386—08 32 



