THE EUROPEAN CORN BORER AND ITS CONTROL. 37 



a maximum of 32 days and a minimum of 20 days (see Table IX). The 

 duration of each instar and the total duration of the larval period depend 

 upon temperature conditions. 



Table IX. — Duration of Larval Instars and Activity to Nov. SO, 1918- 



Second Generation. 



Barnyard Grass (Echinochloa crus-galli). 



Average diiration of larval period to date. 

 Maximum duration of larval period to date, 

 Minimum duration of larval period to date, 



25.7 days. 

 32 days. 

 20 days. 



