CHAPTER XII 



SOME HUMAN PARASITES 



There is probably neither bird nor beast that does not 

 have as its foes certain minute forms of animal parasites. 

 Sometimes these parasites are permanent and sometimes 

 they are temporary. Some of them are external and some 

 of them are internal. Man himself is no exception, for 

 he is subject to the attacks of many internal parasites 

 and is often greatly annoyed and seriously injured by the 

 work of several external parasites. 



We have already discussed, at some length, the tem- 

 porary parasites, mosquitoes, fleas, bedbugs, and certain 

 flies. There are, however, certain permanent parasites 

 which attack man unless he is very careful in his personal 

 habits and watchful of his contact with other less careful 

 individuals. We refer to the itch mite, the head louse, 

 body louse, and others. It is said that man is subject to 

 the attacks of more than a score of external parasites. 



THE ITCH MITE OF MAN 



Sarcoptes scabiei, var. hominis 



The itch mites are not true insects but are closely related 

 to the ticks and belong to that large group of animals 

 known as the Arachnida, the more familiar examples of 

 which are the spiders. Like the spiders, the itch mites 



300 



