232 



SOME ASPECTS OF ECOLOGY 



PER.CENT^QE HUMIDITY 



25-9 



T3-4 



Fig. 72. Relation between humidity percentage and percentage 

 viability (emergence from the pupa) for Protoparce quinque- 

 maculatiis and its parasite Winthemia 4<-pustulata (broken line). 

 (Adapted from Hefley.) 



instar only varied 1-5 days over a range of atmospheric moisture 

 from to 73*4 per cent., where the temperature remained nearly 

 constant at 27^. The optimum humidity for the parasite at the 



