258 Bionomics of Pediculus 
the 8th; 33 % on the 9th; 8 % on the 10th and *2 % later on the same 
day or on the 11th. 
A test of batches of eggs taken from a stock box, some of which 
must have been laid several days previously, showed that none hatched 
at 15-6°-18-4° C., while at 24-5° C. there was considerable egg mortality, 
and the hatching period was spread over a longer period than usual, 
though not to the extent mentioned by Warburton (1909); at36'l°C. 
hatching was spread over five days and the mortality was not excessive. 
To give some idea of the possible rate of multiplication of P. humanus 
we may estimate the egg period as 12 days and a further 12 days to 
the maturity of the $?. Allowing an average of eight eggs per day, 
spread over a fertility period of 40 days, we find that, during her fife, 
a single $ may have 4160 offspring. 
REFERENCES. 
Bacot (i. 1914). A Study of Bionomics of the Common Rat Pleas, and other species 
associated with human habitation, with special reference to the influences of 
Temperature and Humidity at various periods of the Life History of the Insect. 
Plague Supplement III., Journal of Hygiene, pp. 464-465. 
SiKORA (25. VIII. 1915). Beitrage zur Biologie von Pediculus vesfimenti. Ceniralhl. 
f. Bali., Parasii. u. Infektionskranlh., Jena, lxxvi, pp. 523-537. 
Warburton (1909). Report to the Local Government Board on a preliminary 
Investigation on Flock as a possible distributor of Vermin, and on the Life 
History of the Body Louse, Pedicvlus i^estimenti. Reports to the Local Government 
Board, New Series, No. 2. 
