75 



Passing by the sugar mites which are found in such abundance in the commoner 

 grades of brown sugar, we come to the family Sarcoptidae, which includes a class of mites 



Fig. 64. Fig. 65. 



which infest animals and burrowing under their skin cause irritation and swellings. The 

 most notable and familiar example in this class is the 



Itch Mite (Sarcoptes scabiei). 

 Figure 65 represents a male of this species highly magnified : naturally they are so small 

 as to be distinguished with difficulty by the unaided eye. This tiny, bristly creature lives 

 under the human skin in little tunnels eaten away by itself. In fig. 66 we have one of 



Fig. 66. 



these minute channels represented with the female mite at one end. As she works her way 

 under the skin she lays her eggs behind her as shown in the figure, which hatch in from 

 four to six days. It is said that one mite will lay as many as fifty eggs. The young 

 mites have but six legs, and during their growth change their skin four times, at the final 

 moult acquiring an additional pair of legs, or eight in all. When one of the vesicles 

 caused by this insect is minutely examined a tiny spot will be found upon some part of 

 its surface, this is the point where the mite has entered, and from it a faint line or streak 

 may be traced, usually more or less curved, which is the burrow which the creature has 

 made, and in which it lives. The burrow varies in length, and is sometimes as much as 

 five or six inches long, and at the end, under a slight elevation of the skin, the little pest 

 lies concealed, and if the skin there be gently raised with the point of a needle the mite 

 may be easily extracted, as the little creature clings with its sucker-like feet to any object 

 with which it may come in contact. 



The unpleasant disease referred to is of course occasioned by this mite, and is trans- 

 ferred by those infected to others, sometimes by actual contact, but more frequently by 

 occupying beds with an infected person, or after them. This is readily accounted for from 

 the habits of the mite, which during the day hides under the skin, but is active and leaves 

 its hiding place at night. This pest was formerly much more common than it is now, the 

 more general and free use of soap and water has done much to render it scarce ; still, some- 

 times, when bodies of men are crowded together, with little opportunity to attend to per- 

 sonal cleanliness, it appears and spreads rapidly. 



