Pediculus Corporis 



8S 



The adtdt stage is reached on the eleventh day, after three molts, 

 about fotir 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- 

 foiu- 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 accoimt of their 

 parasiticidal properties, sulphur and balsam of Peru, equal parts, 15 

 to 30 grains to the ounce. 



Phthirius pubis (= P. wgrnnafc), 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. 



