652 



Laura Florence 



mature female averages about 4.(3 millimeters long by 2.19 millimeters 

 at the broadest part of the alxlomcn, and the male averages about 3.9 mil- 

 limeters long by 2.1 millimeter^ broad. The following table gives the 

 average measurements throughout the life history: 



Age 



Instar 



Number 

 of feeding.s 



since 

 preceding 



molt 



Length 

 Cmillimetersj 



Breadth 

 (miUimeters) 



Newly hatched . 

 12 hours 



7 days 



85 days 



9|days 



lOi days 



14 days 



15f days 



15 days 



Mature female . 

 Mature male . . . 





 3 



(?) 

 8 

 1 

 3 

 1 

 4 



1 

 1 



2, 



2, 



2. 



3.00 



3.25 



4.00 



4.60 



3.90 



0.50 

 0.50 

 0.75 

 1.00 

 1.00 

 1.25 

 1.25 

 1.50 

 2.00 

 2.19 

 2.10 



In immature lice the lines along which the tegument ruptures at molting 

 are very distinct. When about to molt the insect raises itself until only 

 the posterior end of the abdomen, and the claws of the second pair of legs, 

 are touching the surface on which it rests, the back has a humped appear- 

 ance, and the head is bent downward at right angles to the body. The 

 first rupture is along the dorsal median line of the thorax and gradually 

 extends caudad to the fifth or sixth abdominal segment and cephalad to 

 the frons, where it divides, passing to the base of each ej-e. Air is sucked 

 up into the pharynx and passes through the alunentary canal to escape 

 at the anus. The body is inflated, pushed through the dorsal ruptures, 

 and so drawn away from the old skin. The l)ody is lowered until it 

 touches the hair or bristle on which the louse is resting, when the legs are 

 fcjldod laterally across it and the ventral surface of the thorax and the 

 abdomen (Plate LVIII, 7). The head and the thorax are gradually drawn 

 upward until the ej^es and the proximal segments of the antennae are 

 seen, disclosing at the same time on the old skin a ventral T-shaped 

 I'uptiu-e, the stem of the T lying along the median line from a. point midway 

 between the bases of the antennae to the prosternum, where there is a 



