FACE-MITES. 47 
are described next, it has been thought best to discuss them 
in this place. 
Face-mites live in the sweat-glands at the roots of hairs 
and in diseased follicles in the skin of the human face, chiefly 
about the nose, eyes and chin where they cause the well- 
known comedones or black-heads; they also occur in a num- 
ber of domesticated animals. Such diseased follicles become 
filled with a plug of fatty matter the upper end of which is 
usually hardened and blackened. If these ‘‘black-heads”’ 
are forced out by pressure the 
minute mites may be found in 
all stages of development. To 
detect them more readily it 
is necessary to dissolve this fatty 
matter in a drop of oil or ether. 
The young mites possess six legs, 
the adults eight; both are quite 
worm-like in appearance, their 
elongated abdomen is_ trans- 
versely wrinkled; their mouth is 
a suctorial beak possessing dag- 
ger-shaped mandibles with two 
palpi. In the adult parasite the 
four pairs of legs are very short, 
two-jointed and each armed with 
four,claws. 
These mites cause no harm 
to man except marring his 
Fig. 24. Face-mite of man, greatly or her beauty, but they et a 
enlarged. Original. verely injure dogs, cats, hogs, 
sheep, horses and cattle; sometimes they even produce upon 
them a scab-like disease called the ‘‘red-mange,’’ and in ex- 
treme cases they can cause the death of their hosts. Dogs 
and cats sometimes suffer very much from their presence, 
and in the case of a dog as many as ten to one hundred and 
more mites have been found in a single hair-follicle. In bad 
cases the hair falls out, and the skin becomes covered with a 
reddish scab, which is very difficult to eradicate, and almost 
never without the loss of all the hair; in fact a cureis consid- 

