ANIMAL PARASITES OF CATTLE. 505 



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

 in about 24 hours, and the larvae or maggots in four or five days de- 

 velop to the pupal stage, which lasts a week or 10 days. From the 

 pupal stage the mature fly emerges. The entire process of develop- 

 ment from the deposition of the egg to the appearance of the mature 

 fly therefore may be completed in two weeks, or even in a shorter time. 

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

 with one of the remedies mentioned above (p. 502). Dipping cattle 

 in a vat provided with splashboards set at the proper angle destroys 

 most of the hornflies present on the animals. Unless the splashboards 

 are used all but a few of the flies succeed in escaping as the cattle 

 plunge into the bath and later return to them. Scattering the drop- 

 pings of cattle with a shovel, or with brush dragged over pastures, in 

 order to insure the rapid drying of the manure and consequent de- 



FiG. 2. — Homflies {Lyperosia irritans) on cow horn. (From Bureau of Entomology.) 



struction of the larvae, 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. 3). 

 They breed in running water and appear in swarms during spring and 

 siunmer, often in enormous numbers, causmg 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. 



Buffalo gnats are more troublesome in bright, sunny weather than 

 when it is cloudy, and animals which have not shed their winter coats 

 suffer more from their attacks than those with smooth coats. Cattle 

 kept in darkened stables are not molested. The application of one 

 of the fly repellents already mentioned (p. 502) may help to protect 



