The temperatiire at which the host is maintained, id. thin the 

 limits obseirved, exerts no apparent influence on the time that 

 different stages remain attached. Postfeeding metamorphosis re- 

 quires the following time; from egg to larva , 32 to 65 days at 

 17°C . to 19°C . ; from larva to nvrnph ; Tour to six days at 30°C . , 

 or 21 to U days at 15^. to JTmTT, or 60 to 75 days at 13°C. to 

 lA*^.; from nymph to adult , ten days at 37°C., or 21 to 38 days at 

 20°C., or Sit. days at l^yc . Away from the host, therefore, tem- 

 perature markedly influences the rate of development. 



Once the female abandons the host, oviposition commences 

 after six to 23 days at 17°G. to 19°C., or after fifty to sixty 

 days at 12°G. Oviposition continues for from fifteen to 56 days, 

 dxiring which period the female lays from 3000 to 5770 eggs. 



Nuttall's average minimum times and Theiler's minimum and 

 maximum times for various periods of the life cycle are summarized 

 as follows: 



PERIOD 



DAYS 



Nuttall (1913B) Theiler (1943B) 



Total 



115 



63-202 



Field observation indicates the extreme importance of knowing 

 not only the temperature but also relative humidity at which all 

 rearing experiments such as these are accomplished. 



*Eggs require three months for hatching in wintertime. South Africa. 



- 608 _ 



