164 
Biology of Pediculus humanus 
Longevity of Lice (Different Stages) when Starved. 
The first observation relating to the longevity of lice is recorded by 
Swammerdam (ed. 1682, p. 60) who states that lice soon die unless kept 
warm and moist. Recent publications contain many references to the 
subject because of its practical bearing, but the observations recorded 
are of very unequal value. Very few authors give the requisite data 
regarding (a) the number, age, and stage of development of the lice 
experimented upon, (b) the temperature and hygrometric conditions, 
(c) whether the insects had been fed or not prior to fasting, (d) whether 
the lice were kept in the dark or the light. All of these factors may 
materially affect the results obtained. In the following table I have 
sought to condense the information that is forthcoming from the writings 
of other authors and my own experiments: 
Experimental Records relating to the Longevity 
of Starved Lice. 
(a) Cor for is. 
(a) Records which state the temperature at which the lice were 
kept, and the stages that were experimented upon. 
Exferiments on \ st stage larvae. 
The following records relate to experiments of mine, conducted 
with larvae (Lot 212) collected in batches of 10 for each test as soon as 
possible after hatching. Some larvae remained unfed, others were fed 
once immediately before they began their fast. 
Unfed oi- 
Temp. once fed Longevity when fasting 
°c. 
at start 
Conditions 
(abbreviations: d. 
= dead; f. = 
feeble) 
33° 
unfed 
wristlet, 
23 hrs. 
27 hrs. 
dark 
7 d. 1 f. 
2 d., last 
one dy 
ing 
33° 
fed 
ditto 
9 d. 1 f. 
last one 
dead 
O 
O 
<N 
unfed 
on cloth, 
58 hrs. 
71 hrs. 
81 hrs 
95 hrs. 
101 hrs. 
dark, dry 
3d. 
4 d. 2 d., 1 dying — 
— 
o 
O 
''N 
fed 
ditto 
2 d. 
1 d. 
3d. 
2 d., 1 dying 1 d., last dying 
12° 
unfed 
ditto, but 
57 hrs. 
72 hrs. 
101 hrs 
120 hrs. 
127 hrs. 
damp 
1 d. 
2 d. 
2 d. 
1 d. 
4 dying 
12° 
fed 
ditto 
2d. 
2 d. 
2 d. 
2d. 
Id., 1 dying 
