620 



DISEASES OF CATTLE. 



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 an- 

 noyance caused by these 

 flies, cattle often do not 

 thrive as they should dur- 

 ing seasons when hornflifis 

 are numerous. The horn- 

 fly has also been charged 

 with transmitting diseases, 

 such as anthrax. 



The fly lays its eggs in 

 freshly dropped cow ma- 

 nure. They hatch in about 

 24 hours, and the larvse or 

 maggots in four or five 

 days develop to the pupal 

 stage, which lasts a week 

 or 10 days. From the pu- 

 l^al stage the mature fly 

 emerges. The entire proc- 

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

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

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

 with one of the remedies mentioned above (p. 518). Scattering the 



Fig. 6. — Hdrnfiy (Hwmatolia scrrata) in resting 

 position. (Prom Bureau of Entomology.) 



Fig. 7. — Hornflies iHamatolia serrata) on cow horn. (From Bureau of Entomology, i 



droppings of cattle with a shovel, or with brush dragged over pas- 

 tures, in order to insure the rapid drying of the manure and conse- 

 quent destruction of the larvse, is, when practicable, an efficient means 

 cf reducing the number of these flies. 



