292 ENTOMOLOGY FOR MEDICAL OFFICERS 



The Tyroglyphidce may concern the medical officer not 

 only by their ravages among food-stuffs, but also as some- 

 times getting on to people who have to deal with infested 

 provisions, and causing the skin-disease known as grocer's 

 itch. Occasionally also they or their eggs may be swallowed 

 in cheese or dried fruit, and if they are numerous may cause 

 dysenteric symptoms. 



Some of the species of Glycyphagus hsive a predilection 

 for sugar ; in them the integument is rough, the claws of the 

 legs are very inconspicuous, and some of the hairs of the body 

 are feathered. 



Tyroglyphus includes the familiar cheese-mite, which lives 

 in all sorts of provisions besides cheese. The dorsal integu- 

 ment is smooth; the cephalothorax is separated from the 

 abdomen by a suture ; the pedipalps are inconspicuous ; the 

 legs end in a distinct claw and a sucker, and the first leg of 

 the male is not thickened. 



The genus Akurobius (aXew/)0)/ = flour) includes the single 

 well-known species A. farince, which infests flour and grain 

 as well as other provisions. It differs from Tyroglyphus 

 chiefly in having the pedipalps quite distinct from the 

 rostrum and the first leg of the male thickened. 



The species of Carpoglyphus are found in dried fruit and 

 jam. The integument is smooth, there is no suture between 

 the cephalothorax and abdomen, and the claws of the legs 

 arise from the tip of a membranous extension of the 

 tarsus. 



Family Demodicidce. The minute mites of the one genus 

 Demodex that constitutes this family live in the sebaceous 

 glands of mammals and several of the domestic animals. 

 The body is elongate and tapering, and its hinder part is 

 superficially ringed and almost worm-like. The appendages 

 are stumpy. These microscopic parasites do little or no 

 harm to their hosts. 



Family Eriophyidm {Phytoptidce). Minute mites that form 

 galls, blisters, and excrescences on the plants on which they 

 live. They resemble the Demodicidce in general form, but 

 have only two pairs of legs. 



The mites of the following eight families are of no parti- 

 cular importance from the medical standpoint : 



