THE HORN FLY OF CATTLE. 



a 



The Horn Fly of Cattle; a, the egg; b, the larva or niaggot; c, the pupa; d, the 

 adult fly. (The flue black lines at the sides ot the figures indicate the natural size 

 of the specimens.) [After Riley.] 



Of the amount of damage done by the fly, Messrs. Riley and 

 Howard (Insect Life, loc. cit.) say: 



The amount of damage done by the fly has been exaggerated by some, 

 and underestimated by others. We have heard many rumors of the death 

 of animals from its attacks, but have been unable to substantiate a single 

 case. We believe that the flies alone will never cause the death of an 

 animal. They r reduce the condition of stock to a considerable extent, 

 and, in the case of milch cows the yield of milk is reduced from one- 

 fourth to one-half. It is our opinion that their bites seldom produce 

 sores by themselves, although we have a number of cases where large 

 sores had been made by the cattle rubbing themselves against trees and 

 fences, in an endeavor to allay the irritation caused by the bites; or in 

 spots where thej 7 could not rub, by licking constantly with the tongue, 

 as about the bag and on the inside of the hind thighs. A sore once 

 started in this way will increase with the continued irritation hy the flies, 

 and will be difficult to heal. Those who underestimate the damage 

 believe that the flies do not suck blood; but such persons have doubtless 

 watched the flies only upon the horns or. elsewhere in their resting posi- 

 tion, when the beak is not inserted, or have caught them and crushed 

 them when their bodies contained little blood. In reality, the flies suck 

 a considerable amount of blood, however, and it is their only nourishment; 

 if captured and crushed at the right time, the most skeptical will be 

 convinced. 



c 



