bb. No distinct spiracle in the stigmal plate on each side of the body. c. Body usually coriaceous, with few hairs, with a specialized seta arising from a pore near each posterior corner of the cephalothorax; no eyes; mouth parts and palpi very small; ventral openings of the abdomen large; tarsi without sucker. Not parasitic. ORIBATOIDEA. cc. Body softer; without such specialized seta. d. Aquatic species. HYDRACHNOIDEA. dd. Not aquatic. e. Palpi small, three segmented, adhering for some distance to the lip; ventral suckers at genital opening or near anal opening usually present; no eyes; tarsi often end in suckers; beneath the skin on the venter are seen rod-like epimera that support the legs; body often entire. Adults frequently parasitic. SARCOPTOIDEA. f. With tracheæ; no ventral suckers; legs ending in claws; body divided into cephalothorax and abdomen; the female with a clavate hair between legs I and II. Usually not parasitic on birds and mammals. TARSONEMIDÆ g. Hind legs of female ending in claw and sucker as in the other pairs. PEDICULOIDINÆ To this sub-family belongs the genus PEDICULOIDES P. ventricosus is described on page 69. [Illustration: 155. Margaropus winthemi, male. After Nuttall and Warburton.] [Illustration: 156. Margaropus winthemi, capitulum and scutum. After Nuttall and Warburton.] gg. Hind legs of the female end in long hairs. TARSONEMINÆ TARSONEMUS INTECTUS Karpelles, normally found upon grain, is said to attack man in Hungary and Russia. Other species of the genus affect various plants (c.f. fig. 150, g). ff. Without tracheæ; no such clavate hair. g. Genital suckers usually present; integument usually without fine parallel lines. h. Legs short, without clavate hair on tarsi I and II. On insects. CANESTRINIDÆ. hh. Legs longer, with a clavate hair on tarsi I and II. Not normally parasitic except on bees. TYROGLYPHIDÆ i. Dorsal integument more or less granulate; claws very weak, almost invisible; some hairs of the body plainly feathered; ventral apertures large. GLYCIPHAGUS Her. This genus occurs in the United States. In Europe the mites have been found feeding on all sorts of substances. They are known as sugar mites and cause the disease known as grocer's itch. G. DOMESTICUS and G. PRUNORUM are old world species (fig. 150, d).