26 



BULLETIN 173, U. S. DEPARTMENT OF AGRICULTURE. 



1909, with figures 9 and 10, showing the record for 1910, it will be 

 seen that the time of emergence in any considerable numbers was 

 much shorter in 1910 than was the case in 1909. No actual daily 

 emergence records were kept in 1911, but no thrips were found in 

 the field until February 18 and then only very few in one early 

 almond orchard. On February 24 a few scattering specimens were 

 found in two pear orchards. Not until March 12 were they appearing 

 in any noticeable numbers, but the emergence was very rapid after 

 this, reaching the maximum between March 15 and 20. The emer- 

 gence of adults was mostly over by March 30. 



22 



/2 



- 



CO 



+ 



^ssqp 4 



-.-- 1 



* I 









pi'ik'T 'M " '"' ' 



■ 







/8' 



Fig. 6.— Type of wooden cage used for field emergence records of the pear thrips in orchards at 

 Walnut Creek, Suisun, and Courtland, Cal., 1909-10. (Original.) 



Emergence records and field observations in the Suisun Valley of 

 Solano County (see Table VII and fig. 11) show that for the season 

 of 1910 thrips came out of the ground in numbers on about the same 

 dates as for Contra Costa County. They were out in numbers in the 

 Courtland district of Sacramento County from two to • four days 

 earlier. Further observations in 1911 showed the emergence in 

 these two sections to be about the same time as for Contra Costa 

 County. 



Records of the emergence for the years 1909, 1910, and 1911 are 

 summarized in Table IV. From this table it will be seen that in 

 Santa Clara County in 1909 most thrips appeared on March 3 while 

 in 1910 March 4 yielded the highest number, with March 3 and 2 



