48 FACE-MITES. 



ered impossible by many veterinarians. The illustration 

 (fig. 24) shows the general appearance of an adult face-mite 

 of man. 



There are a number of so-called species found upon dif- 

 ferent hosts, but all are verj^ similar, and the description 

 and figure of one is sufiicient for all. 



The Face-Mite of Man {Demodex {Slmonea) foUicuIormn 

 Sim.) (fig. 24) was discovered in 1842 by Simon. It is not a 

 dangerous parasite to man, but if transmitted to a dog, as was 

 purposely done, the mites rapidlj^ increase upon this new 

 host and in a short time cause very serious trouble. In man 

 these mites prefer such parts of the face as are free from 

 hairs. They are very small, the male measuring 0.30 by 

 0.04 mm., the female 0.40 by 0.05 mm., the heart-shaped 

 ■tgg is 0.08 mm. long. 



The Demodex of the Dog {D. foll/ciiloriim var. eanis) was 

 discovered in 1844 by Tulk. Its head is almost square. This 

 parasite produces at first small swellings, which gradually 

 unite in large sores containing 50 to 500 and more mites; 

 such sores are chiefly found upon the throat, breast, abdo- 

 men and inner surfaces of the thighs. 



The Demodex of the Cat {D. folJkuJorum var. cat!) was 

 discovered b}^ Leidy in the noses and ears of cats infested bj^ 

 Sarcoptes minor. This species is exceedingly small, and in- 

 fests most frequentlj^ the head of its host. 



The Demodex of the Hog (/>. phylloides suis) was discov- 

 ered in 1878 by Csoker. 



Other species of Demodex occur upon the cow, sheep and 

 deer. 



The Demodex of the dog especially is a very dangerous 

 parasite, and b\^ no means very uncommon, causing an almost 

 incurable disease, the red scab or mange; and whenever it 

 finds a home upon an unfortunate dog the animal soon be- 

 comes ill and dies. This mite prefers the hair>^ skin of the 

 host. Here it causes either a disease of a squamose nature, 

 in which the epidermis becomes scurfy, the hair drops out, 

 with little inflammation, or of a pustulose form with intense 

 inflammation and the formation of pustules in and about the 



