400 



STATE AGRICULTURAL COLLEGE BULLETINS. 



to attract special attention till 1889. Since that time it has spread 

 throughout the eastern part of the United States and from the Gulf of 

 Mexico into Canada. It reached Michigan late last season and was 

 reported from Manchester and several other places in the southeastern por- 

 tion of the State. The rapidity with which it spreads is wonderful. As 

 many of the stock farms will probably receive a visit this season a knowl- 

 edge of the fly and its habits, along with the best means of thwarting 

 severe attacks, will be opportune. 



For a thorough study of the habits and life history of the fly we are 

 indebted to Dr. Riley and his assistants of the Department at Washington, 

 D. C.,* and to Prof. Smith of the New Jersey Stat8on,t who both investi- 

 gated it independently and have suggested about the same remedies. 



Fig. 3. a, egg; 6, imago; c, head from the side; d, mouth parts. The line at the right shows the 

 natural size of the fly. All are greatly magnified. (After Smith). 



The name horn fly is given this species because of the habit of settling 

 on the base of the horns when resting. When very numerous the flies 

 will cover the base of the horns for several inches so completely that they 

 cannot be seen. This habit is especially noticeable in the early part of the 

 season. But little if any injury is done by the fly while here, except by 

 its presence to keep stock that is inclined to be nervous, in an uneasy con- 

 dition. The real worry and harm comes when the flies are feeding on the 

 stock. They bite quite like the mosciuito, pierce the flesh by the use of a 

 find lancet, shown at d (Fig. 3), and then sucking the blood through the 

 tube or sheath. A small amount of iritating saliva is secreted in the 

 operation and this causes congestion around the wound and probably more 

 pain than the piercing. While in the act of biting the flies bury them- 

 selves in the hair with the wings remaining spread as shown in the cut. 

 This is very characteristic of the fly. It enables them to rise out of dan- 

 ger very quickly should the tail or head be thrown in that direction, but 

 they are back and at work again as (quickly as they left. When numerous 

 the effect upon thin skinned stock is to set them almost frantic; while 

 others may not mind it nearly as much. The tendency upon all, however, 

 is to reduce them in flesh, and with dairy cows to also decrease the flow of 



* Insect Life, Vol. IT, pp. 93-108. 



+ Bulletin No. 62, of the New Jersey Agricultural Experiment Station, Nov., 1889. 



