soa 



SANITARY EXT():\I( !L()G Y 



Tlie liody, luad. and juihic lice are found on all races of men and 

 seem to show some varietal differences according to the host. None 

 of these s]iecies occurs on any other liost than man, although a closely 

 related s])ecies Pcdlculus corisobrinus Piaget occurs on a monkey (Ateles 

 pcntadact /iJus). 



Children and old people are much more likely to be affected with head 

 lice than active men and women, and girls because of their long hair are 

 much more fre(juently infested than boys. On the other liand, men 

 seem to be more often the subjects of attack by corporis and pubis. 



In the civilian population of this country there are indications of im- 



Plate XXI. — The clntliiiijj louse, Pediculmt corporis. Fig. 1. — Female, ventral view. 

 Fig i. Male, dorsal view. (Pierce and Hutchison, photos by Dovener.) 



portant changes in the general problem. In times of peace the louse 

 problem is most acute in jails, pooi'houses, and like institutions; among 

 vagrants and the extremely poor classes ; among gangs of laborers, as in 

 construction camj)s, lumber camps, threshing gangs, etc. ; and among im- 

 migrants. Since our entrance into the war there have been economic 

 changes which have shifted some of these centers of infestation. For 

 example, tliere have been many camps of laborers etigaged in temporary 

 construction work. Reports indicate that lice give consideraljle trouble 

 in some of these. There has probably been an increase in the size and 

 number of lumber camps. On the other hand, we have been informed by 

 the captain in charge of the House of Detention at New Orleans, that 

 the vagrant population, which has always been their worst source of 



