SarcoptidcB, or Itch Mites 



73 



Sarcoptes scabiei, male. 

 (X 100). After Fursten- 

 berg. 



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 Sarcoptidce 

 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 roimded and of a somewhat reddish 

 tinge, and much smaller. The body is 

 marked by transverse striae 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- 

 2 40 (A in length, and 1 5 0-2 00 [a in breadth, 

 possesses pedunculated suckers on each 



pair of legs except the third, which bears, instead, a long bristle. 



The female (fig. 56) 3oo-450[ji in length and 250-350(1, 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, 



timnels into the skin; the males remain 



under the superficial epidermal scales, and 



seldom are fotmd, as they die soon after 



mating. 



As she burrows into the skin the female 



deposits her eggs, which measure about 



150 X looji. Fiirstenberg says that each 



deposits an average of twenty-two [to twenty-four eggs, though 



Gudden reports a single burrow as containing fifty-one. From these 



566. 



Saicoptes scabiei, female. 

 (X ino.) After Pursten- 

 berg. 



