442 ABACHNIDA 



1. Tyroglyphus Latreille, Body elliptical, with a suture between 

 the second and third pairs of legs; male w^ith 2 suckers on each side of 

 the genital pore; mandibles chelate; a sucker at the 

 top of each foot: about 8 species. 



T. siro (L.). Cheese mite. Length .G mm.; 

 width ,3 mm. ; color whitish : in old cheese and sim- 

 ilar substances. 



T. farinae (DeGeer) (Fig. 695). Length of 

 male .5 mm. ; of female .3 mm. ; color whitish : in flour, 

 grain, and stored foods; cosmopolitan; often a pest. 



T. linterni Osborn. Similar to the above, but 



T3^ „„_ smaller and with very lono- bristles extending back- 



Fig. 695 .7 & » 



Tyroglyphus farinae Avards from the body : in mushrooms. 

 (Banks). '^ 



2. Rhizoglyphus Claparede. Suture between 

 the second and third pair of legs; mandibles chelate; male with ventral 

 suckers; feet short, with stout claws and spines: 2 species. 



R. hyacinthi (Boisduval). .Bulb mite. Length .75 mm.: burrows 

 into the bulbs of cultivated plants, giving entrance to fungi and bac- 

 teria; often a pest in hot and green houses. 



Family 6. OEIBATIDAE.* 



Horny or beetle mites. Body minute and divided into 2 parts by a 

 transverse suture; integument hard, with few hairs; a bristle, which is 

 often long, prominent, and club-shaped, and is called the pseudostig- 

 matic organ, arises from a depression near the hinder margin of the 

 cephalothorax on each side (Fig. 696, 1) ; mouth parts and pedipalps 

 small and hidden beneath the head; mandibles chelate; claws 1 or 3; 

 the young are often very bizarre in shape: about 20 genera with over 

 300 species, which feed principally on vegetable or decaying animal mat- 

 ter and are not parasitic, but live in moss, grass, among decaying leaves, 

 in crevices of bark, etc. 



Key to the genera of Orihatidae here described: 



«i Abdomen with a pair of wing-like expansions 1. Galumna 



aj No such expansions. 

 6i Cephalothorax with a pair of dorso-lateral ridges. 



Ci Body smooth 2. Liacarus 



Cj Body rough ; cephalothorax and abdomen not distinctly separated. 



3. SCUTO VERTEX 



bg No such ridges ; 8 claws on each leg. 



dj Body flat, often rectangular 4. Nothrus 



d.. Abdomen very high with concentric rings 5. Neoliodes 



* See "On the Oribatoidea of the United States," l)y N. Banks, Trans. Am. Ent. 

 See, Vol. 22, p. 1, 1895. "Orihatidae," by A. D. Michael, Das Tierreich, 1898. "New 

 Orihatidae from, the United States," by N. Banks, Uroc. Acad. Nat. Sci., Phila., 190G, 

 p. 490. 



