PARASITIC DISEASES 



THE HOG LOUSE 



Hamatopinus suis — Linnaeus 



The hog louse is the only common external 

 parasite of swine; As well as the largest, it is 

 the most common louse found on domestic ani- 

 mals, and because of its size and the thinness of 

 the hog's coat, can be readily seen. It is generally 

 found on the thin parts of the, skin (back of the 

 ears, on the inside of the thighs, etc.) that are 

 more easily penetrated by the mouth parts of the 

 parasite. Unthrifty pigs and adults may become 

 badly infested, but on thrifty, active animals the 

 invasion is not as great because of their ability 

 to resist it. Lice are seldom found on hogs that 

 have been shipped some distance, especially dur- 

 ing the warm weather. The coat affords the lice 

 but little protection, and they become' dislodged 

 when hogs are crowded together and sprinkled 

 with water. 



Description. — The hog louse is a blood-sucking 

 parasite and the largest species of the family. The 

 female, when grown, is fully one-fourth of an inch 

 long, biit the male is smaller. The latter is also 

 distinguished by a dark streak on the middle and 

 ventral surface of the last three abdominal seg- 



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