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 very similar, and the description 
and figure of one is sufficient for all. 
The Face-Mite of Man (Demodex (Simonea) folliculorum 
Sim.) (fig. 24)was discovered in 184.2 by Simon. It is nota 
dangerous parasite to man, butif transmitted toa dog, as was 
purposely done, the mites rapidly 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 
egg is 0.08 mm. long. 
- The Demodex of the Dog (D. folliculorum var. canis) was 
discovered in 1844 by Tulk. Itsheadis 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. folliculorum var. cati) was 
discovered by Leidy in the noses and ears of cats infested by 
Sarcoptes minor. This species is exceedingly small, and 1in- 
fests most frequently the head of its host. 
The Demodex of the Hog (D. 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 by 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 hairy 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 
