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. 30, 1918 — 



Second Generation. 



Barnyard Grass (Echinochloa crus-galli). 



Date of 

 Hatching, 19 



August 6, 

 August 6, 

 August 6, 

 August 6, 

 August 9, 

 August 9, 

 August 9, 

 August 9, 

 August 9, 

 August 9, 

 August 14, 

 August 14, 

 August 14, 

 August 14, 

 August 14, 

 August 14, 



Duration of Larval In- 

 stars IN Days. 



Date of 



Pupation 



1918. 



Sept. 14 



Days in 

 Larval 

 Period 



to Date. 



Activities to 

 Nov. 30, 1918. 



Spun web Sept. 24. 

 cf adult Oct. 14. 

 Died Nov. 19. 

 Died Sept. 6. 

 Spun web Sept. 11. 

 Died Nov. 15. 

 Spun web Nov. 30. 

 Died Nov. 3. 

 Spun web Oct. 8. 

 Spun web Oct. 10. 



Still feeding Nov. 



30. 

 Not emerged Nov. 



30. 

 Spun web Oct. 21. 



Still feeding Nov. 



30. 

 Still feeding Nov. 



30. 

 Spun web Oct. 16. 



Average duration of larval period to date, 

 Maximvim duration of larval period to date. 

 Minimum duration of larval period to date, 



25.7 days. 

 32 days. 

 20 days. 



