284 



THE ARACHNOIDS 



bristles, but in the male, the fourth pair has suckers. The tunnels made by the 

 female have the egg-bearing female at the blind end; scattered all along are fasces, 

 eggs, larvae; the eggs being next the mother and the more mature young at the en- 

 trance to the gallery. A diagnosis can be made from the finding of either eggs or 

 larvae. The eggs are 140^ long and hatch out in four to five days. A female 

 becomes mature in about two weeks. 



In treating itch with sulphur preparations the adult females and immature itch 

 mites are killed; the eggs, however, are not affected. Hence a second treatment 

 about ten days after the first is necessary to kill the young mites, which have devel- 



- l_. AV E.R V 



FIG. 78. Arachnoidea exclusive of ticks. (ia) Sarcoptes scabiei, female; 

 (ib) S. scabiei, male; (2) Demodex folliculorum; (3) Trombidium akamushi, hexapod 

 larva (Kedani mite); (4) Trombidium holosericeum larva (Leptus); (5) Dermanyssus 

 gallinae; (6) Tyroglyphus longior; (ja) Pudiculoides ventricosus, male; (76) P. ventri- 

 cosus, young female; (jc) P. ventricosus impregnated female; (8) Porocephalus 

 armillatus; (go) Linguatula serrata, female; (96) L. serrata, larva. 



oped subsequent to the first treatment, 

 of itch mites. 



Different animals have different species 



Demodicidae (Hair Follicle Mites). 



Demodex folliculorum. This is a vermiform acarine about 400^ long; the eggs 

 are about 75^ long; they chiefly live in the sebaceous glands of nose and forehead. 



Tarsonemidae. 



This acarine family shows a complete sexual dimorphism. The Pediculoides 

 ventricosus is oval and about 125X75," for the male which has claws at the extremi- 



