THE MORE IMPORTANT FAMILIES OF AC ART, 



117 



Many live free and feed on fresh or dead animal or vegetable substances ; 

 others are parasitic on mammals or birds ; others feed only on hairs or feathers. 

 Hence they are found literally everywhere. Generall}^ their mandibles are short, 

 not protrusive, and end in short and stout nippers, like those of a lobster. Their 

 palps are generally filiform and short. Their legs are short, in some instances 

 extremely short, or even rudimentary, and are arranged in four groups o£ two 

 each, like in the foregoing group, to which they are very closely related. The 

 female genital aperture is generally placed far forward, that of the male behind 

 the middle of the ventral surface. The followino- curious facts are worth notin o-. 





Fig. 18. — Aleurobius africana, 

 Oiidms. ; female ; dorsal side. 

 Oriffinal. 



Fig. 19. — Sarcopte.s egui^ (lerl. ; female : 

 dorsal side. — Copied from M^giiiii, Les 

 paras, et les malad. paras., tab. 9 ; 1880. 

 A noxious species. 



As in Lepidoptera, the females, or rather the female deutonymphs, are 

 provided with a special copulatory opening or projecting tube, and the males 

 generally pair not with the mature females but with the deutonymphs. In 

 these cases the nubile deutonymphs only develop into mature females after 

 fertilization. To this group belong, among others, the following Families : 

 the Tyroglyphid^ (Cheese Mites), which maybe found on all kinds of animal 

 and vegetable victuals (fig. 18), in decaying leaves, in mosses, in mushrooms, 

 etc. Sometimes they abound in houses, stores, churches, etc., swarming 

 in such numbers as to cause considerable annoyance. In most of these 

 instances they have been introduced in the so-called vegetable horse-hair 

 (vegetable fibres from Haifa-grass and dwarf-palms), and soon disappear. 



