12 BULLETIN 3 8, PUERTO RICO EXPERIMENT STATION 
The whipworm, Trichuris suis (fig. 2, F), is a white worm found 
in the caecum and colon. The anterior portion of the body is 
long and slender and the posterior portion short and thick. The 
anterior portion is embedded in the lining membrane of the intestine. 
Whipworms are often found in pigs and calves but usually infes- 
tations are light. The control measures are the same as given for 
the nodular worms. 
The liver fluke, Fasciola hepatica, is a leaflike flatworm found 
in the ducts of the liver of cattle, goats, and swine. This worm 
is common in pigs that have access to swampy ground. Among 
slaughtered animals a loss occurs in that infested livers are con- 
demned. Pigs should be prevented from feeding in marshes and 
should not be fed grass obtained from these areas. Directions for 
fluke control are given in a previous publication of the station. 3 
The thin-necked bladderworm, Cysticercus tenuieollis, consists of a 
spherical cyst about 2% cm (1 inch) or more in diameter. The ex- 
ternal tough membrane encloses a thinner transparent membrane 
having a projecting neck and head, the scolex of the tapeworm. This 
inner cyst is filled with a watery fluid. These bladderworms are 
usually embedded in the liver or attached to other viscera in the 
abdominal cavity. The adult tapeworm is found in the intestine 
of the dog. In natural infestations, which consist usually of one 
or two cysts, no symptoms are observed in the pig. The cysts should 
be removed at time of slaughter and destroyed. The deep burying 
or destruction by burning or otherwise of carcasses of animals dying 
in the field is another indicated control measure. 
EXTERNAL PARASITES 
Although several kinds of arthropods or external parasites occur 
on the hog in Puerto Rico, on the whole they are not considered of 
much importance. The hardy native pig exposed to plenty of 
sunlight on the open range seems to be remarkably free from external 
parasites. However, infestations occur, especially among pigs con- 
fined in insanitary quarters, which are detrimental to health and 
control measures are necessary. 
The hog louse, Haematopin m adventicius, causes considerable dam- 
age to hogs if present in large numbers. In some herds, especially 
of the improved breeds, this louse is connnonly present for years. 
Under conditions such as exist in Mayaguez this louse is not noticeable 
except during the hot weather of April and May before the start of 
the regular, torrential showers, when it increases in numbers. It does 
not seem to spread and is rarely if ever found on the native hogs 
brought to the abattoirs. 
These lice can be eradicated by hand applicat ions, sprays, medicated 
hog wallows, or dipping. Hand applications may consist of (1) 
crude petroleum, (2) crank-case drainings, (3) cottonseed oil and 
kerosene, equal pa i ts, or (4) lard 1 pound to one-half pint of kero- 
sene. These remedies should be distributed in a thin, even coating 
over- the entire surface of the head and body, including the inner 
surface of the ears and between the thighs. Freshly oiled or greased 
• Van VOLKBNBDROj II. L. PARASITES AND PARASITIC DISEASES OP CATTLE IN PUERTO 
HICO. Puerto Rico .\fsr. BJxpt. Sta. Bull. .".(5, p. 18. 1984. 
