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Biology of Pediculus hnmanus 
Man may become infested by pediculi directly or more or less 
indirectly. Infestation may occur in the following ways: 
(1) Contact with healthy verminous persons. In individuals infested 
with pediculi, especially when these are numerous, the insects frequently 
stray away from their habitat. No doubt the scratching and restlessness 
induced by the presence of lice promote the wandering of the parasites. 
In common with others, I have frequently seen head-lice wandering on 
the hair and body-lice upon the clothing of verminous persons. Such 
wandering lice may pass readily from one person to another by contact. 
Thus the contact of children’s heads at play may suffice to spread 
capitis, or merely brushing past an infested person may suffice to pick 
up an occasional corporis. Prolonged contact or close association 
with verminous persons is certain to lead to infestation sooner or later. 
Such close association is afforded in poor tenements, but this war has 
brought better examples in billets, dug-outs, military prisoners’ camps 
and the like, where soldiers have huddled or been herded together, thus 
affording the best possible means for the dissemination of lice. Peacock 
(1916, p. 44) has observed that body-lice tend to wander when men’s 
surroundings are warm and comfortable, for instance when men are 
sleeping closely crowded together 1 . If the present general prevalence 
of pediculosis in the fighting forces could be traced back to its sources 
it would certainly be found to be due to the introduction of lousy 
recruits among those that were clean. The former came from the slums 
and distributed their surplus lice to their companions who were handi¬ 
capped by having to wear their clothing continuously. 
(2) Contact with the sick, dying, and verminous dead. When an 
infested person is dying or has died, the insects wander out from their 
retreats in the clothing or hair. This behaviour of lice in abandoning 
the dead or dying recalls that of fleas and some ticks under similar 
circumstances. The scattering of the lice upon and about the body, 
is a phenomenon that has frequently been observed by those that have 
visited verminous individuals upon their deathbeds, or who have 
handled them when dead. As examples may be cited the following: 
Denny (1842, p. 14) saw capitis wandering in myriads all over the body 
of an old man who died in a much neglected condition at Leeds; many 
of the lice congregated about the nostrils, eyes, and corners of the mouth. 
1 I cannot confirm the statement by Warburton (1911) that corporis larvae are more 
prone to wander than the adults, for I find that both wander equally when hungry and the 
temperature is suitable. A fertilized female or two once established on a person would 
soon establish a flourishing colony, the conditions being suitable 
