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. 





emergmg. 



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 I'll. — Emergence records of pear ihrips for Suisun, Solano County, Cal., 191Q. 





Emergence of thrips 



Emergence of thrips 

 from cages placed 

 in ground under 

 trees in orchards, 

 Suisun, Cal. 



from soil samples 

 la ken from or- 

 chards in Dec em- 

 ber and January 

 and kept in cages 

 at laboratory, Sui- 





sun, Cal. 





Number of 





Number of 



Date. 



Ihrips 



Date. 



thrips 





emerging. 





emerging. 



Feb. 17 



3 



Feb. 16 



1 



19 







17 



3 



21 







18 



2 



23 







19 



6 



25 



1- 



20 



1 



27 



20 



21 



1 



Mar. 1 



47 



22 



4 



3 



121 



23 



2 



10 



484 



24 



5 



16 



1 



25 



11 







26 



11 







27 



14 







28 



41 







Mar. 1 



105 







2 



247 







3 



243 







7 



612 







12 



357 







16 



82 







19 



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- 



