TILE l'EAli Til KIPS IN CALIFORNIA. 



27 



following close 4 behind. The increase in emergence during the season 

 1009 (fig. 12) and the tapering off in the same year was more gradual 



300 



275 



250 



225 



200 



/75 



/50 



/25 



/OO 



75 



50 



25 



O 

































































































































































































































































































































































































































































































































































































/2 /4 /6 /& 20 22 24 26 2ff 2 4 6 e /O /2 /4 /6 /& 20 22 24 26 2& 



Fig. 7.— Curve illustrating emergence of adult pear thrips at laboratory, Walnut Creek, Cal., 1909. 



(Original.) 



than during the season 1910 (fig. 13). This difference was most 

 probably influenced during the latter season by the temperature. 



800 

 750 

 700 

 650 

 600 

 550 





































































































































































































































500 

 450 

 400 













































































































































350 

 300 

 250 











































































































































200 

















































/50 

















































/OO 

















































50 

















































O 

















































/4 /6 /& 20 22 24 26 2i 

 / r ErBf?L/s4/?V 



? 2 4 6 & /O /2 /4 /6 /& 20 22 24 26 Z 



9 



Fig. 8.— Curve showing emergence of pc^r thrips in cages under trees in field at Walnut Creek, Cal., 



1909. (Original.) 



RELATION OF EMERGENCE TO TEMPERATURE AND RAINFALL. 



The average mean temperature for February and March, 1911, or 

 the two months when practically all of the thrips emerged, was 



