TYROGLYPHID.E 5 ir 



Family. Tyroglyphidae. 



Very small mites without eyes and without tracheae, with smooth skin. 



The males usually have a suctorial pore on either side of the anus, which is used 

 during copulation, or suckers may be found in both sexes near the sexual orifice. 

 The mouth parts form a cone with chelate cheliceras, and three-jointed pedipalpi ; 

 the legs are usually short, have five segments with a terminal claw and suckers, or 

 either one or other of these organs. The numerous species and genera live free and 

 from choice in slowly decomposing vegetable and animal matter (cheese, cereals, flour, 

 sugar, preserves, dried anatomical preparations, bacon, dried fruits and fungi), also in 

 the corners of dwellings, etc. ; they incidentally get into or on to man, or are found in 

 chamber utensils and in spittoons ; actual parasites are rarely found amongst them. 



[The chief genera are Tyroglyphus, Rhizoglyphus, Glyciphagus, Aleurobius 

 and Histiogaster. The first three have typical characters referred to, but are 

 distinguished from each other by the two former having the hairs on the dorsum 

 smooth, whilst in Glyciphagus they are hairy, plumose, or feathered. Rhizoglyphus 

 can be told from Tyroglyphus by having claws on the tarsi without any suckers ; 

 Tyroglyphus has both claws and suckers. The larvae are hexapod and may become 

 adult in the usual way by repeated moults, or they enter the so-called hypopial 

 stage. In this the eight-legged nymph becomes quiescent, and during this stage 

 it fixes itself to some insect or other animal by a patch of suckers on the lower 

 surface of the hind end of the body, and is so carried from place to place. The 

 hypopus does not feed and has a hard shell and short legs. When it has reached 

 a new home it moults and development proceeds in the normal way. Canestrini 

 and Kramer treat the Tyroglyphidce as a sub-family of the Sarcoptidtz, calling them 

 sub-family Tyroglyphince,\ht other sub-families being Sarcoptince, CanestriniincE and 

 Analsina:. F. V. T.] 



Sub-family. Tyroglyphinae. 

 Genus. Aleurobius, Canestrini. 



Aleurobius (Tyroglyphus) farinae, de Geer (part), Koch. 



The male measures 0*33 mm. in length by 0*16 mm. in breadth; 

 the female 0*6 mm. in length by o'3 mm. in breadth. These mites 

 possess five pairs of suctorial organs of a light colour ; the legs are 

 reddish. Moniez observed them in Lille on the skin of labourers 

 who had been unloading Russian corn. A few of the species 

 generally mentioned under the designation of Tyroglyphus siro are 

 probably the common flour-mite, which also occurs on dry cheese. 



[The farincv of de Geer is an Aleurobius described by him in 1778 

 (" Mem. Hist. Ins.," vii, t. 5, f. 15, p. 97) as Acarus farincc. F. V. T.] 



Genus. Tyroglyphus, Latreille. 



Tyroglyphus siro, L., 1756. 



(Defined by Gervais, 1844.) 



Male 0-5 mm. in length by 0-25111111. in breadth ; female 0-53 mm. 

 in length by 0*28 mm. in breadth ; the males have two suckers on the 

 tarsi of the fourth pair of legs. Penis straight, colour whitish or 

 reddish. 



