76 



BULLETIN" 429,, U. S. DEPARTMENT OE AGRICULTURE. 



the third generation, showing the average length of the periods 

 The sum of the averages of the stages is found to be 



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NVO<0»C^I\l^OO>»N<0<0*Oj(\|>»00>«)K<olr>*<«>C^^OO l ^N.<Blo*P)CV|^Oo\«)-N<o"0*'^<V| , » 





42.9 days, while the average length of the total life cycle of this gen- 

 eration is 43.11 days, a difference of but 0.2 days. 



