ARACHNIDA AND MYRIAPODA 



131 



The itch mite (Sar copies scabei), causing the itch in man, 

 and Demodex folliculorum, the parasite sometimes present 



FIG. 150. Demodex folliculorum enlarged one thousand 

 times. After Selenka. 



in the human hair follicles, are Arachnida much changed 

 on account of their parasitic habits. The minute jigger 



FIG. 151. Scorpion showing the sting at the posterior end. Photograph natural 

 size. 



or chigger, so numerous in old berry patches in the South- 

 ern and Central States, often causes great inconvenience 

 by burying itself beneath the human skin. 



