14 LICE AND THEIR MENACE TO MAN 



function, of which we know nothing definite except 

 that they guide the movements of the insect. 

 Behind the antennae are the black eyes, which 

 are simple, in contradistinction to the eyes of 

 higher insects such as the house-fly, the eyes of 

 which are compound and made up of many 

 elements, to each of which the simple eye of the 

 louse corresponds. The latter is probably able 

 to see no more than is necessary to enable it to 

 distinguish shades of light. The thorax narrows 

 from behind forwards and bears the six legs. 

 The legs are jointed and end each in a single 

 large claw which has a slightly serrated edge ; 

 the first pair being larger in the male than in 

 the female. The claw has a similar movement 

 in relation to the rest of the leg as the blade of 

 a penknife has to the handle, but does not close 

 so completely down on it. In the space between 

 claw and leg hairs or fibres are gripped tightly 

 by the insect when it is walking, and it is by 

 means of them that it clings to cloth and hair 

 even after death. There are never any wings, 

 and the louse is quite unable to jump. The 

 abdomen is divided into a number of segments 

 by means of slight constrictions at the sides 

 and rings round the body which can be faintly 

 seen. In the adult female the abdomen is 

 broader and heavier than in the male, while the 

 tip turns slightly down and is slightly forked. 

 In the male it is more barrel-shaped, cylindrical, 

 and the single-pointed tip is turned up. The 



