PEDICULUS CAPITIS 



395 



i. Pediculus capitis, De Geer, 1778. 



Male i 1-5 mm. in length, female i'8 2'o mm. in length. The 

 colour varies from light grey to black according to the colour of 

 the hair of the human race upon which they are parasitic. The 

 abdomen has eight segments, of which the six central ones are 

 each provided with a pair of stigmata. The thorax is as broad as 



the abdomen. Eggs O'6 mm. in length; about 



fifty are deposited by a female Head Louse. 



The young can propagate when eighteen days 



old. 



The head louse lives especially in the hairy parts of 

 the head of human beings ; more rarely it is found en 

 other hairy parts of the body. It is spread over the 

 entire surface of the globe, and was present in America 

 before the arrival of Europeans. Quite exceptionally 

 it is said that it bores itself deep into the epidermis 

 and can live in ulcers. , 



[The eggs are pear-shaped and are attached to the hairs near the roots 

 by means of a clasping collar. They hatch in about seven days. The young 

 are like the adults and mature in a month. Its general colour varies with 



FIG. 251. Mouth 

 parts of Pediculus 

 vestimenti. After 

 Denny (enlarged). 



FIG. 252. Ovum 

 of the head 

 louse, 70/1. 



FIG. 253. Head louse, male, 15/1. 



FIG. 254. Pediculus vesti- 

 menti, Burm. 15/1. 

 Adult female. 



that of its host. In West Africans nearly black, in Hindoos dark and 

 smoky, on Chinese and Japanese yellow, on Hottentots orange, on South 

 American Indians dark brown (Murray). F. V. T.] 



