AQ Farmers’ Bulletin 1150. 
the older sheep taking the more dangerous pasture, where it is neces- 
sary for sheep to go back to old pasture within a year. It may be 
mentioned in passing that hillside pastures are apt to be safer than 
bottom land, as they benefit by the cleansing action of heavy rains 
and the following run-off, as well as holding less moisture, lack of 
moisture being very unfavorable to the worms. Rich bottom pastures, 
on the other hand, are the ones which are least likely ‘to have an in- 
fection washed off and are apt to have the eggs and larve from the 
hillsides above washed on to them. The more or less abundant mois- 
ture, moreover, is highly favorable to these worms. It is precisely 
these bottom pastures which are likely to be used for young animals, 
as they present the best growth of grass and are most attractive. 
In a plan of rotating pastures to keep down ‘stomach worms, 
the sheep may be moved over cornfields, hayfields, and stubble of 
various sorts. During freezing weather, the eggs and nonresistant 
early stages of the young worms on pasture diminish as they are 
killed by freezing, so that the pastures at this time, while still in- 
fected, do not become increasingly dangerous. Plowing is a means 
by which infestation may be controlled, the young worms being 
turned under and buried; apparently they do not get back to the 
surface in numbers sufficient to cause serious trouble. Such plowed 
land may be sown to forage crops and the sheep turned in on these 
crops with safety. When different kinds of stock are rotated on 
pastures, sheep may safely follow horses or swine, but not cattle 
or goats as these latter also may be infected with stomach worms 
and a number of other worms common to sheep, goats, and cattle. 
If the preventive measures outlined here are not possible, sheep 
may be given the copper-sulphate treatment, preferably in doses 
three-fourths as large as those where one treatment is given, once 
every six weeks from spring until freezing weather. 
THE NODULAR WoRM.'® 
Location.—The adults of the nodular worm live in the large in- 
testine of the sheep. The larval worms live in nodules in the wall 
of the large and small intestine, and occasionally make their way 
to the mesenteric lymph glands, the omentum, or the liver. The 
nodules are most numerous in the wall of the large intestine. 
Appearance.—The female worms attain a length of 15 mm. (about 
five-eighths inch), the males being a little shorter (fig. 26). Both 
sexes have a-characteristic solid white color. The head is bent over 
and forms a- hook with the body. 
_ Life history.—The details of the life history of this worm are not 
completely known. The eggs from the female in the large intestine 
18°"Proteracrum Columbianum. Synonym, Gsophagostomum columbianum. 
——eE 
