296 SUMMER MANAGEMENT 



Summer Enemies of the Flock. — After the shepherd has pro- 

 vided ample pasture, forage, water, salt, shade, and shelter for his 

 flock in summer, he must still remember that there are certain 

 insidious enemies which he must guard against. Most of these 

 enemies are parasitic in nature and hence hard to combat. The 

 most common and the most dreaded of these parasites in farm 

 flocks is the stomach worm. 



Stomach Worm. — The stomach worm {Hwmonchus contortus) 

 made its first deadly attack upon the flocks in the central part of 

 the United States in 1893 and 1894. It was probably brought to 

 this country in sheep imported from England. At any rate, it was 

 a new enemy to those who had handled Merinos, and when the 

 savage attack of 1893 and 1894 came, nearly all flock owners in the 

 middle-western section of the United States were nonplussed and 

 helpless. Thousands of lambs and many old sheep died in Ohio, 

 Michigan, Indiana, and Illinois. Hundreds engaged in sheep rais- 

 ing were so discouraged that they closed out their flocks and gave 

 up sheep forever. Since that time, a large percentage of the native 

 lambs sent to the open markets have been badly infested with 

 stomach worm. Being unthrifty and unfinished, they have been 

 the object of scathing criticism on the part of commission men 

 and buyers for the packers. Sheepmen are gradually learning how 

 to keep the stomach worm in check, but it is still an insidious 

 enemy that is sure to bring trouble to the farm, flock owner who 

 is not always keenly alive to the possibility of its presence (Fig. 

 189). 



Life History of the Stomach Worm. — To Eansom,^ of the 

 Zoological Division of the Bureau of Animal Industry, more than 

 to anyone else, belongs the credit of determining the life history of 

 the stomach worm. He learned what takes place from the time the 

 worms mate until the sheep become infested, or perhaps reinfested. 

 The mating process takes place in the abomasum (known as the 

 fourth or true stomach of the sheep), where all of the worms live 

 while in the host, except a few that drift over into the duodenum. 

 The eggs, which are microscopic, are deposited in the abomasum 

 and pass out of the body in the feces. Heat hastens the time of 

 hatching, which may occur in a few hours, days, or weeks, accord- 



" Circulars 93 and 102, U. S. Bureau of Animal Industry, Waahington, 

 D. C. 



