268 Hominoxious Arthropods 



known as grocer's itch. G. domesticus and G. pru- 

 . norum are old world species (fig. 150, d). 

 ii. Dorsal integument not granulate; claws distinct; no 



prominent feathered hairs; ventral aperture small, 

 j. Mandibles not chelate; elongate, and toothed below; 

 body without long hairs; palpi enlarged at tip and 

 provided with two divergent bristles. Species feed on 



decaying substances Histiostoma Kram. 



jj. Mandibles chelate; palpi not enlarged at the tip, nor 



with two bristles. 



k. No clavate hair on the base of tarsi I and II; no 

 suture between cephalothorax and abdomen. Live 



on bees or in their nests Trichotarsus Can. 



kk. A clavate or thickened hair at the base of tarsi I and II. 



I. The bristle on the penultimate segment of the legs 



arises from near the middle; no suture between the 

 cephalothorax and abdomen. The species, some 

 of which occur in the United States, feed on dried 

 fruit, etc Carpoglyphus Robin. 



II. The bristle on the penultimate segment of the legs 



arise from near the tip; a suture between cephalo- 

 thorax and abdomen. 



m. Cephalothorax with four distinct and long bristles 

 in a transverse row; tarsi I and II about twice 

 as long as the preceding segment (fig. 150 f) 



Tyroglyphus Latr. 



n. Some bristles on tarsi I and II near middle, 

 distinctly spine-like; the sense hair about its 

 length from the base of the segment. Several 

 species in the United States belong to this 

 group. 



nn. No spine-like bristles near the middle of the 

 tarsi ; sense hair not its length from the base 

 of the segment. 



o. Of the terminal abdominal bristles, only two 



are about as long as the abdomen; leg I 



of the male greatly thickened and with a 



spine at apex of the femur below . . T. f arinae. 



oo. Of the terminal abdominal bristles at least 



six or more are very long, nearly as long 



as the body. 



p. Bristles of the body distinctly plumose or 

 pectinate; tarsi very long. .T. longior. 

 pp. Bristles of the body not pectinate. 



q. In mills, stored foods, grains, etc. Third 

 and fourth joints of hind legs scarcely 

 twice as long as broad; abdominal 

 bristles not unusually long; legs I 



