466 



ARACHNIDA ACARINA 



CHAP. 



Fam. 1. Sarcoptidae. — No tracheae or stigmata. Apical 

 rostrum. Oviparous or ovoviviparous. The seventy genera and 

 530 odd species of this family are divided into a number of 

 sub-families, of which the principal are the 

 Sarcoptinae, the Analgesinae, and the Tyro- 

 glyphinae. 



(i.) The Sarcoptinae are the so-called " Itch- 

 mites." They are minute animals, with bodies 

 transversely wrinkled and legs terminating in 

 suckers or bristles. The genus Sarco23tes, 

 which includes about fifteen species, hves in 

 tunnels which it burrows in the skin of 

 mammals. 



(ii.) The Analgesinae are the " Birds'- 

 feather Mites." The principal genera are 

 Fterolichus (120 species), Pteronyssus (33 

 species), Analges (23 species), Megninia (42 

 species), and Alloiotes (33 species). 



(iii.) The Tyroglyphinae ^ have received the 

 popular name of " Cheese -mites," from the 

 best known example of the group. They 

 are smooth-bodied, soft-skinned white Mites, 

 with legs usually terminating in a single claw, 

 sometimes accompanied by a sucker. They 

 are for tlie most part carrion-feeders, living 

 upon decaying animal or vegetable matter, 

 but a few are parasitic on mammals, insects, 



Fig. 241. — A, Leg of a 

 fowl infested with 

 " leg - scab " ; B, 

 female of Sarmptes ^^^ ^ormS. 

 mutans, greatly 

 magnified. (After 

 Neumann. ) 



There are sixteen genera, including about 

 fifty species. Tyroglyphus siro and T. longior 

 are common Cheese -mites. Other species live in decaying 

 vegetables and food -stuffs. Some of the genus Glycyphagus 

 {G. palmifer, G. jplumiger) are very remarkable for the palmate 

 or plumose hairs which decorate their bodies. The remarkable 

 hypopial stage in the development of Tyroglyphus has been 

 mentioned on. p. 463. The Tyroglyphinae are the lowest of the 

 free-living Acarine forms. 



1 See Michael, British Tyroglyphidac, published by the Eay Society, 1901-2. 



