1906. 



1 individual to 200 

 acres. 



1907. 



5 individuals to 200 

 acres. 



190S. 



69 individuals to 200 

 acres. 



1909. 



176 individuals to 200 

 acres. 



1910. 



15,625 individuals to 200 

 acres. 



1911. 



270,156 individuals to 200 

 acres. 



DIAGEAM III —Illustrating the increase in average abundance of an introduced insect 

 which disperses as indicated by Diagram I. and increases at the rate indicated by 

 Diagram 11. 



