ACARINA 283 



and attack both man and animals. The condition (itching and redness) produced 

 is at times called autumnal erythema. There is a Trombidium in Mexico which 

 has a predilection for the skin of the eyelids, prepuce, and navel. The Kedani mite, 

 an orange-red larval mite about 250 by 125 microns is believed by the Japanese 

 authorities to bring about infection with Japanese river fever or Tsutsugamushi, 

 as the result of transmitting either a bacterium or protozoon by its bite. The 

 disease somewhat resembles typhus, although an eschar at the site of the bite and 

 lymphatic involvement is present. 



Gamasidae. 



Of the Gamasidae. which generally have a hard leathery body and 1 styliform 

 piercing chelicerae, delicate five jointed palps and styliform hypostome, only the 

 Dermanyssus gallinse is of interest. This coleopterous mite infests chicken-houses 

 and sucks the blood of the inmates. They will also attack man. Poultrymen may 

 be troubled with a sort of eczema on the backs of the hands and forearms, similar 

 to scabies, resulting from bites by these mites. They measure 350X650^. They 

 have no eyes. 



Tyroglyphidae. 



Mites of this family live on cheese, flour, dried fruits, etc. They are small, 

 without eyes, and have a smooth skin and a cone-like appearance of the mouth 

 parts which are largely formed by the chelate chelicerae. They are chiefly of 

 importance because of their being occasionally found in urine, faeces, etc., and being 

 striking objects, the question of pathogenicity arises. The T. longior has been 

 associated with intestinal trouble (probably a coincidence, patient having eaten 

 cheese containing these mites). 



Glyciphagi are found in sugar and are the cause of what is known as "grocers' 

 itch." Rhizoglyphus parasiticus is reported to be the cause of an itch-like affection 

 of the feet of coolies on tea plantations. To distinguish: the dorsum of Glyciphagus 

 is hairy or plumose; Tyroglyphus has both claws and suckers on tarsi, while Rhizo- 

 glyphus has only claws. 



Sarcoptidae. 



These are small eyeless mites with a transversely striated cuticle. They live 

 on the epidermis of man and various animals. The rostrum is chiefly made up of 

 chelate chelicerae with quite short three jointed, rather adherent palpi. It is the female 

 that makes the tunnels in the skin between the fingers, on penis, flexor surface of 

 forearm, etc. The male dies off after copulation. The female passes through four 

 stages: i. larva; 2. nymph; resembles adult, but has no sexual organs; 3. the pubes- 

 cent female; 4. the egg-bearing female. A pair of itch mites may produce 1,500,000 

 descendants in three months. Transference of eggs, larvae or pubescent females 

 does 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 250X150^; the female is 

 about 400X300^. Besides the difference in size, the male may be distinguished from 

 the female by the fact that the third and fourth pairs of legs in the female have 



