THE PEAR THEIPS IN CALIFORNIA. 



29 



°F. 



Average mean temperature for month of February, 1910 49. 



Mean maximum temperature for month of March, 1910 66. 2 



Mean minimum temperature for month of March, 1910 44. 5 



Average mean temperature for month of March, 1910 55. 



Mean maximum temperature for month of February, 1911 56. 5 



Mean minimum temperature for month of February, 1911 37. 3 



Average mean temperature for month of February, 1911 46. 9 



Mean maximum temperature for month of March, 1911 63. 3 



Mean minimum temperature for month of March, 1911 46. 



Average mean temperature for month of March, 1911 54. 6 



2200 

 2/0O 

 ZOOO 

 J900 



teoo 



/700 

 /600 

 /500 

 f400 

 /300 

 /ZOO 

 //OO 

 /OOO 

 900 



eoo 

 yoo 



600 



soo 



400 

 300 

 200 

 /OO 



Fig. 10. — Curve showing emergence of adult pear thrips in cages under trees in field, at Walnut Creek, 



Cal., 1910. (Original.) 



It will be seen from the temperature records (Table II) that while 

 February, 1909, had 2 degrees higher average mean temperature 

 than February of 1910, March of 1909 had 5 degrees less average 

 mean temperature than March of 1910, making the average mean 

 temperature for the months in which most of the adults emerged 

 50.5° F. in the year 1909 and 52° F. in the year 1910. Another factor 

 which held back the emergence greatly the former year was the 





































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































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 A44f?CH 



