383 
THE BIOLOGY OF PHTHIRUS PUBIS. 
By GEORGE H. F. NUTTALL, F.R.S. 
{From, the Quick Laboratory, University of Cambridge.) 
(With 9 Text-figures.) 
CONTENTS. 
PAGE 
Introduction ........... .383 
I. Prevalence and modes of dissemination of Phlhirus . . . 384 
Prevalence on man.384 
Occurrence on other hosts than man ..... 38,5 
Distribution of Phthirus on man’s body ..... 38.5 
' Cases of general infestation in adults ..... 385 
Cases of infestation confined to the head .... 38(i 
Infrequency of head infestation .... . 387 
Why does P/d/m'Ms infest the head so rarely? . . . 388 
Modes of dissemination and infestation ..... 388 
II. Method of raising Phthirus experimentally . . . .391 
III. Special biology of Phthirus ....... 392 
Proportion of the sexes on the host ..... 392 
Copulation .......... 392 
Oviposition.394 
Hatching .......... 396 
Development from larva to adult—moulting—raising records 396 
Duration of the life-cycle.406 
Longevity . , ........ 400 
Feeding habits ......... 401 
Reactions to light and heat.402 
Summary and Conclusions ........ 103 
Introduction. 
Most of what has been stated witli regard to the main features in 
the biology of Pedicidus Jmmanus (see p. 82), likewise applies to Phthirus 
pubis. The habits of the latter species differ, hotvever, in one particular 
which requires special mention, i.e. the insect is relatively immobile 
when upon the host, remaining attached and feeding for hours or days 
on one spot without removing its mouthparts from the skin into which 
it has bored them. 
