Pediculus Corporis 
85 
The adult stage is reached on the eleventh day, after three molts, 
about four days apart. Adults enter into copulation about the 
fifth day and as the eggs require eight days for development, 
the total cycle, under favorable conditions, is about twenty- 
four days. Warburton’s data differ considerably from those com¬ 
monly quoted and serve to emphasize the necessity for detailed studies 
of some of the commonest of parasitic insects. 
Body lice are voracious feeders, producing by their bites and the 
irritating saliva which they inject, rosy elevations and papules which 
become covered with a brownish 
crust. The intense itching pro¬ 
vokes scratching, and character¬ 
istic white scars (fig. 67) sur¬ 
rounded by brownish pigment 
(fig. 68) are formed. The skin 
may become thickened and take 
on a bronze tinge. This mela¬ 
noderma is especially marked 
in the region between the shoul¬ 
ders but it may become genera¬ 
lized, a prominent characteristic 
of “vagabond’s disease.” Ac¬ 
cording to Dubre and Beille, 
this melanoderma is due to a 
toxic substance secreted by the 
lice, which indirectly provokes 
the formation of pigment. 
Control measures, in the case 
of the body louse, consist in 
boiling or steaming the clothes or in some cases, sterilizing by dry heat. 
The dermatitis may be relieved by the use of zinc-oxide ointment, 
to which Pusey recommends that there be added, on account of their 
parasiticidal properties, sulphur and balsam of Peru, equal parts, 15 
to 30 grains to the ounce. 
Phthirius pubis (= P. inguinalis ), the pubic louse, or so-called 
“crab louse,” differs greatly from the preceding in appearance. It is 
characterized by its relatively short head which fits into a broad 
depression in the thorax. The latter is broad and flat and merges 
into the abdomen. The first pair of legs is slender and terminated 
by a straight claw. The second and third pairs of legs are thicker 
67. Pediculosis in man caused by the body 
louse. After Morrow. 
