650 
Conditions 
On hog 
Room of ordinary humidity, at 
temperature of 85° F., in Septem- 
ber 
Same conditions, but eggs kept in a 
closed dish containing a recep- 
tacle filled with water 
Temperature by day of 26° C. and 
by night of 35° C. 
Incubator at constant temperature 
of 37° C., dry heat 
In vials, worn constantly next the 
LAURA FLORENCE 
Eggs hatched after 
From 13th to 20th day, 
maximum about 16th 
Authority 
Watts 
Stevenson 
Sikora 
11 to 12 days (5 eggs 
hatched, out of 24).. Florence 
14 days (9 eggs hatched, 
body OUutof 19) eee Florence 
Conditions as in last preceding 13 days (4 eggs hatched, 
Out Of. 5) > ani eee Florence 
The period of incubation evidently lies between twelve and twenty days, 
with a minimum period of about thirteen to fourteen days when the eggs 
are kept constantly at body temperature. It is interesting to compare 
this with the recent work of Bacot and Linzell (1919:388), who found 
the incubation period of the eggs of the horse louse, Haematopinus asinz, 
to be apparently from sixteen to twenty days, and the minimum period 
under natural conditions about fifteen to sixteen days. 
In the course of their development hog lice undergo three molts, and 
rearing in captivity has proved the cycle from egg to egg to occupy from 
twenty-nine to thirty-three days. The life history, as we have observed 
it, is summarized in the following table: 
Time from laying to hatching of eggs.............. ' 13 to 15 days 
First) molt/occurredgattenws: suis eae ara 5 to 6 days 
Second moltoccurredvalvenmts: 0 oe. ceed emcee 4 days 
hind} moltoccurred? alters 0.2 ee ws 6 vere oii eine 4to 5 days 
Sexual: maturity occurred afters. .2 pte oe ee 3 days 
