51 



U.S. Entomologist for 1889 and 1890. Prof. J. B. Smith, of New Jersey has published 

 a very full account of his investigations of the same subject in New Jersey Agricultural 

 Experimental Station Bulletin No. 62. The figures used in this article have been very 

 kindly lent for the purpose by Prof. Riley. 



The color of the Horn-fly is dark gray with yellowish sheen, and the body is covered 

 with black bristles. The head consists almost entirely of the dark-red silvery-edged eyes. 

 It will be at once distinguished from the common Cattle-fly by its darker colour, smaller size, 

 greater activity and, above all, by the characteristic habit from which it takes its name, 

 of gathering in clusters upon the horns of cattle, particularly upon the upper side. When 

 very abundant the flies form a more or less complete ring around the horn, sometimes ex- 

 tending two or three inches from the base towards the tip, as shown in fig. 31. This 

 clustering on the horns seems to be peculiar to the species, and is probably due to some 

 special characteristic. They merely settle there, however, as a convenient resting place, 

 from which they cannot be easily dislodged by the animal ; for the same reason, they also 

 congregate in clusters at the base of the tail and on the neck. Strange to say, while the 

 closely allied Stomoxys calcitrans bites the legs of cattle very much, the Horn fly very 

 seldom settles there, and while the Stomoxys bites men, dogs and horses, the present 



Fig. 31. 



Cow-horn showing band of resting flies — reduced. 



(Figure kindly lent by the United States Entomologist.) 



species has not been recorded to give trouble in that way. A milkman, however, told me 

 that on one occasion he was much bothered by Horn-flies biting his bare arms when milk- 

 ing, and that the bite was much more severe than that of the common Cattle-fly. It is 

 probable that they will occasionally bite human beings, particularly when, as in the above 

 instance, working with bare arms among cattle, and thus getting their odor on the skin. 



Cattle of all breeds are subject to annoyance from this pest, but I have observed 

 very great diflPerences in susceptibility to injury, not only in different breeds, but also in 

 individual animals of a given breed according to the health of the animals, temperament 

 or the texture of their skins. 



When feeding, the flies work their way down through the hairs until they can pierce 

 the skin of their victims with their short beaks. They are exceedingly agile, and when 

 biting keep their wings partly spread, ready to take flight at the least disturbance. A 

 slash of the tail or a swing of the head of a bitten animal only disturbs its tormentors for 

 a second, when they will rise in a cloud but to settle again and resume the operation of 

 torture the next instant. The bites seem to produce great irritation, and sores are fre- 

 quently formed on the necks and bodies of animals by their rubbing themselves against 

 posts or trees or by licking bitten places, where the irritation cannot be allayed by rub- 

 bing, as inside the thighs, around and on the udder and along the milk vein. 



