512 



DISEASES OF CATTLE. 



THE HORNFLY (LYPEROSIA IRRITANS).i 



This fly, now found nearly everywhere in the United States, was 

 introduced into this country from Europe about the year 1885. 

 Hornflies have the habit of clustering about the base of the horn 

 (fig. 7) , whence the name by which they are popularly known. They 

 do not damage the horn, and congregate there only to rest. 



In view of the general practice of dehorning cattle, the name horn- 

 fly is less distinctive than it once was. Moreover, hornflies rest on 

 other parts of the body as well as the horns. 



When resting, their wings are held down close to the body (fig. 6) ; 

 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 which 

 are out of reach of the ani- 

 mal's head ot tail. Unlike 

 most flies, they remain on 

 the animal more or less con- 

 stantly, day and night. Ow- 

 ing probably to the irrita- 

 tion and annoyance caused 

 by these flies, cattle often 

 do not thrive as they should 

 during seasons when the 

 flies are numerous. The 

 hornfly 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 

 21 hours, and the larviie or 

 maggots in four or five days develop to the pupal stage, which lasts 

 a week or 10 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 may be completed in tAvo 

 Aveeks, or even in a shorter time. To protect cattle from attacks 

 of the hornfly they may be treated Avith one of the remedies men- 

 tioned above (p. 510). Dipping cattle in a vat provided Avith splash- 

 boards set at the proper angle destroys most of the hornflies present 

 on the animals. Unless the splashboards arc used all but a fcAV of the 

 flies succeed in escaping as the cattle plunge into the bath and Inter 



Pio. 6 

 tion, 



-Hornfly (Lifperosia irritans) in resting posi 

 Enlarged. (From Bureau of Entomology.) 



1 For fnrtlier information consult Circular 115 of tlic Bureau of Entomology. 



