48 Farmers’ Bulletin 1150. 
the shell, the skin that separates at the second molt, however, remain- 
ing on the larva. The larva hatches under the influence of alternate 
moistening and drying or of temperatures of 24° to 32° C. (75° to 
90° F.). Like the stomach worm, the ensheathed larva then ascends 
blades of grass under favorable conditions of temperature and 
moisture, and is taken in by sheep as they feed. ‘These larve are 
very racibbane to cold and drying, and have also been found to live. 
in water for over 11 months. In the intestine of the sheep the larve 
develop to adult worms. 
Distribution.—At least one species of these worms (J. spathiger) 
appears to be quite common in sheep in the United States. 
Symptoms and lesions——When present in small numbers it is un- 
likely that these worms do much damage, but sheep infested with 
large numbers have been found to be unthrifty. So far the only 
symptoms that may be attributed to them are those commonly asso- 
ciated with gastrointestinal parasitism in general—those of mal- 
nutrition. No definite lesions have yet been described for this worm. 
Treatment.—The treatment for infestation with this worm has not 
yet been worked out. Oil of chenopodium, as given for hookworm, 
is worth trying. As previously noted, the removal of these worms 
may prove difficult. 
Prevention.—The same measures that are of value against stomach 
worms will probably be of value against the thread-necked worms. 
THE WHIPWORM.*! 
Location.—The whipworm occurs in the large intestine, usually in 
the cecum, but rarely elsewhere in the digestive tract. 
Appearance.—The body of this worm is thick posteriorly and very 
slender anteriorly, the anterior portion of the body being two 
or three times as long as the posterior portion, from which fact it 
receives the name of whipworm. The thick portion is comparable to 
a whip handle and the thin portion to a whiplash (fig. 31). The 
male is 5 to 8 em. (2 inches to over 3 inches) long, with the anterior 
portion of the body three times as long as the posterior portion. The 
male spicule is 5 to 6 mm. long, and has a long sheath, covered with 
spines, and terminating in a palbaus enlargement. The female is 5 
to 7 em. long, with the anterior portion of the body twice as long as 
the posterior portion. The eggs of the whipworms are characteristi- 
cally lemon-shaped. 
Life history.—So far as is known this worm has a simple life his- 
tory. The eggs produced by the adult worm pass out in the feces - 
21 Trichuris ovis. 
