650 Laura Flokence 



Conditions Eggs hatched after Authority 



On hog From 13th to 20th day, 



maximum about 16th 



day Watts 



Room of ordinary humidity, at 

 temperature of 85° F., in Septem- 

 ber From 15 to 16 days Stevenson 



Same conditions, but eggs kept in a 

 closed dish containing a recep- 

 tacle filled with water 12 days Stevenson 



Temperature by day of 26° C. and 



by night of 35° C. 17 days Sikora 



Incubator at constant temperature 11 to 12 days (5 eggs 



of 37° C, dry heat hatched, out of 24.) , . Florence 



In vials, worn constantly next the 14 days (9 eggs hatched, 



body out of 19) Florence 



Conditions as in last preceding 13 days (4 eggs hatched, 



out of 5) Florence 



The period of incubation evidently lies between twelve and twentj^ days, 

 with a minimum period of about thirteen to fourteen daj^s 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 tlie eggs of tlie horse louse, Haematopinus asini, 

 to be apparently from sixteen to twenty days, and the minimum period 

 under natural conditions about fifteen to sixteen days. 



In the course of tlieir development hog hce undergo three molts, and 

 rearing in captivity has proved the cycle from egg to egg to occupy from 

 twenty-nine to tliirty-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 occurred after 5 to 6 days 



Second molt occurred after 



4 days 



Third molt occurred after 4 to 5 days 



Sexual maturity occurred after . 



3 days 



