Sarcoptidce, or Itch Mites 
73 
and their distribution are much used in classification. The mites 
live on or under the skin of mammals and birds, where they produce 
the disease known as scabies, mange, or 
itch. Several species of the Sarcoptidae 
attack man but the most important of 
these, and the one pre-eminent as the 
“itch mite” is Sarcoptes scabiei. 
The female of Sarcoptes scabiei, of man, 
is oval and yellowish white; the male 
more rounded and of a somewhat reddish 
tinge, and much smaller. The body is 
marked by transverse stria? which are 
partly interrupted on the back. There 
are transverse rows of scales, or pointed 
spines, and scattered bristles on the 
dorsum. 
The male (fig. 56) which is from 200- 
240^ in length, and 150-200^ in breadth, 
possesses pedunculated suckers on each 
pair of legs except the third, which bears, instead, a long bristle. 
The female (fig. 56) 300-450^ in length and 2 5 o-3SO[a in breadth, has 
the pedunculated suckers on the first and second pairs of legs, only, 
the third and fourth terminating in bristles. 
The mite lives in irregular galleries from 
a few millimeters to several centimeters in 
length, which it excavates in the epidermis 
(fig. 57). It works especially where the 
skin is thin, such as between the fingers, 
in the bend of the elbows and knees, and 
in the groin, but it is by no means restricted 
to these localities. The female, alone, 
tunnels into the skin; the males remain 
under the superficial epidermal scales, and 
seldom are found, as they die soon after 
mating. 
As she burrows into the skin the female 
deposits her eggs, which measure about 
150 x 100^. Fiirstenberg says that each 
deposits an average of twenty-two to twenty-four eggs, though 
Guddcn reports a single burrow as containing fifty-one. From these 
56a. Sarcoptes scabiei, male. 
(X 100). After Fiirsten- 
berg. 
