34 



BULLETIN 173, U. S. DEPARTMENT OF AGRICULTURE. 



Table VI. — Emergence of pear thrips from soil samples taken from orchards in December 

 and January and kept in cages at laboratory, Walnut Creek, Contra Costa County, Cal. 





Number of 





Number of 



Date. 



thrips 



Date. 



thrips 





emerging. 





emerging. 



1909. 





1910. 





Feb. 12 



3 



Feb. 18 



11 



15 



42 



20 



16 



16 



56 



22 







17 



38 



24 



12 



18 



56 



26 



30 



20 



89 



28 



75 



23 



125 



Mar. 2 



377 



25 



185 



4 



918 



27 



246 



6 



937 



Mar. 1 



196 



8 



165 



4 



237 



10 



114 



7 



51 



12 



47 



10 



52 



14 







14 



13 



16 



4 



19 











22 











Table VII. — Emergence records of pear thrips for Suisun, Solano County, Cal., 1910. 



Emergence of thrips 

 from cages placed 

 in ground under 

 trees in orchards, 

 Suisun, Cal. 



Emergence of thrips 

 from soil samples 

 taken from or- 

 chards in Decem- 

 ber and January 

 and kept in cages 

 at laboratory, Sui- 

 sun, Cal. 



Date. 



Number of 



thrips 

 emerging. 



Date. 



Number of 



thrips 

 emerging. 



Feb. 17 

 19 

 21 

 23 

 25 

 27 



Mar. 1 

 3 

 10 

 16 



3 

 

 

 



1 



20 



47 



121 



484 



1 



Feb. 16 



17 

 18 

 19 

 20 

 21 

 22 

 23 

 24 

 25 

 26 

 27 

 28 

 Mar. 1 

 2 

 3 

 7 

 12 

 16 

 19 



1 



3 



2 







1 



1 



4 



2 



5 



11 



11 



14 



41 



105 



247 



243 



612 



357 



82 



8 



The latest dates on which adult thrips were collected in the field 

 were about the same for the years 1909 and 1910, the last ones being 

 found from April 15 to April 25. In 1911 living adults were found 

 as late as the middle of May. They were very scarce, however, after 

 May. The number of living adults as a rule decreases rapidly after 

 April 1. 



The time adults will feed before they begin ovipositing varies. 

 Those individuals which emerge early and which do not have a suit- 



