THE EUROPEAN CORN BORER AND ITS CONTROL. 31 



7.25 days; second instar, 6 days; third iiistar, 5 days; fourth instar, 

 6.5 days; fifth instar, 13 days; sixth instar, 14 days; seventh instar, 

 8 days; and eighth instar, 13 days. The average duration of the total 

 larval period was 44 days, with a maximum of 57 and a minimum of 35 

 days (see Table III). The duration of each instar and the total duration 

 of the larval period depend upon temperature conditions. 



After reaching full growth the larva forms a cocoon within which it 

 pupates. 



Table III. — Duration of Larval Instars — First Generation. 



Pigweed (Amaranthus). 



Dock (Rumex). 



Average duration of larval period 44 days. 



Maximum duration of larval period, .57 day.s. 



Minimum duration of larval period, 35 days. 



