ITCH MITES. 



223 



Sarcoptidae. 



These are small eyeless mites with a transversely striated cuticle. 

 They live on the epidermis of man and various animals. It is the 

 female that makes the tunnels in the skin between the ringers, on penis, 

 flexor surface of forearm, etc. The male dies off after copulation. 

 The female passes through 4 stages: (i) larva; (2) nymph; resembles 



7-oe, 



FIG. 69. Mites, i, Demodex folliculorum; 2, Kedani mite; 3, Trombidium 

 holosericeum; 4 and 6, Female and male Sarcoptes scabiei; 5, Tyroglyphus farinae; 

 7, Rhizoglyphus parasiticus. 



adult, but no sexual organs; (3) the pubescent female; (4) the egg- 

 bearing female. A pair of itch mites may produce 1,500,000 descend- 

 ants in 3 months. Transference of eggs, larvae or pubescent females 

 do not seem to transmit scabies. It is the egg-laden female only. The 

 human itch mite, Sarcoptes scabiei, is an oval mite, the male is 250 x 150/4; 

 the female is about 400 x 300/4. Besides- the difference in size, the 

 male maybe distinguished from the female by the fact that the third and 



