314 



HOUSEHOLD INSECTS 



transmission actually occurs. The evidence obtained, 

 however, points very strongly in that direction. 



The disease may be carried by other blood-sucking 

 insects. 



THE CRAB LOUSE 



Phthirius pubis (inguinalis) 



The third louse infesting man is very distinct from the 

 other two in general appearance. Its body is short and 



broad, in fact, 

 nearly as wide as 

 long. The legs are 

 very stout, espe- 

 cially the two hind 

 pairs, and are al- 

 ways spread out 

 laterally, thus in- 

 creasing the appar- 

 ent width of the 

 body. The body, 

 as a whole, reminds 

 one of a crab, hence 

 its common name, 

 "crab louse" (Fig. 108). This louse is whitish in color 

 w r ith a dusky patch on each shoulder and the legs are 

 tinged with red. 



It inhabits the pubic region particularly, but is found in 



the arm pits, and in the beard and occasionally among the 



hairs of the eyebrows, and has been reported on the head. 



This louse is evidently more easily communicated from 



one individual to another than either of the other species. 



FIG. 108. Crab louse. (X 20.) 



