Gr. H. F. Nuttali 
165 
From this we see that some unfed and once-fed larvae at 33° C. 
lived up to 27 hours; at 20° C. some lived to 81 and 101 hours; at 
12° C. some lived up to 127 hours. There is no material difference in 
the longevity of unfed and once-fed larvae; only at 20° C. did the fed 
larvae slightly outlive the unfed. 
Other authors state that 1st stage larvae live: 1 day at 36-1° C., 
dry (Bacot 1 )*; 1 day at 25-30° C. (Hase 6 ); 1-2 days at 30° C. (Patton 
and Cragg, 1913. p. 552); at longest 4 days at 6° C. (Hase 6 ). None of 
these authors state whether the larvae had fed or not. 
Experiments on adults. 
Temp. 0 
C. Unfed or fed 
Conditions 
Longevity Authority 
36° 
not stated 
dry. 
3 days f 
Bacot 1 
34° 
99 ••• ••• ••• ••• 
not stated 
1 day 
Heymann 
25-29° 
99 99 *•* ••• ••• ••• 
99 99 
3-5 days 
99 
24° 
99 99 ••• ••• ••• ••• 
damp 
3 days 
Bacot 1 
16-18° 
99 99 *•• **• 
dry 
4-7 days 
„ 
12-15° 
99 99 * • • • • • * • • • • • 
not stated 
7-9 „ 
Heymann 
15° 
8 hrs. after ecdysis, fed soon before, 
2 expts. with 10 lice 
dry, dark, in 
tubes on cloth 
3-4 „ 
Nuttali 
15° 
Several days old, fed soon before, 5 lice 
ditto 
5 days 
99 
10° 
ditto ... . 
ditto 
3 „ 
99 
5° 
8 hrs. after ecdysis, unfed, 2 expts., 10 
lice 
ditto, damp 
3* „ 
99 
5° 
ditto, except that fed shortly before 
ditto, damp 
3 „ 
99 
' * To avoid repetition, the references are arranged by numbers and given at the end of 
this section p. 170. 
f A day is reckoned as 24 hours throughout. 
I here append an unpublished experimental record of Hindle’s relating to adult lice 
of unknown age: 
“Eighteen pairs of lice were allowed to gorge, and then divided into three lots, each 
of six pairs, which were kept at different temperatures without further feeding, with the 
following results: 
Days ■ 30° C. 22° C. 8-10° C. 
1 
2 
3 
4 
5 
6 
7 
8 
1 dead 
4 and 3 $$ dead 
1 and 3 $$ dead 
All dead 
1 <J dead 
5 dead 
1 $ and 5 $$ dead 
1 $ dead 
All dead 
4 (J(J dead 
1 $ and 4 5$ dead 
1 $ dead 
1 $ dead 
All dead 
The period of starvation that a louse can survive thus varies from about three days 
at 30° C. to seven days at 8-10° C.; but those which have been starved for three days at 
room temperature become so weak that they can only feed with difficulty, and there is 
little doubt that a louse, even if it survived a week without a meal, would not then be 
able to feed.” 
