424 JOURNAL OF ECONOMIC ENTOMOLOGY . [Vol. 14 



THRIPS INJURY TO PEACHES IN SOUTHERN CALIFORNIA 



By Geo. P. Weldon, Pomologist, 

 Chaffey Junior College of Agriculture, Ontario, Calij. 



In the fall of 1914 some Elberta peaches were received at the office of 

 the State Commissioner of Horticulture, vSacramento, from Placer County. 

 These peaches showed a type of injury which at that time was not rec- 

 o,e;nized as being due to insects. A number of growers in the vicinity 

 of Auburn and New Castle were com^plaining of damaged peaches which 

 were noticed at the time the fruit was being packed. It was not until 

 the next season that this injury' was found to be due to the attack of 

 some species of thrips. County Farm. Advisor E. 0. AmAuidson, in 

 examining the blossoms of peaches early in the spring of the year, found 

 that they were full of thrips. He later made observations which showed 

 conclusively that the injury which had been observed commonly the 

 previous season was due to this little insect. 



No data is at hand which would enable one to m.ake an estimate of 

 the injury which was done during the years 1914 and 1915 in Placer 

 County, however, it is known that in some sections severe dam.age re- 

 sulted from the attack of this insect. 



In August of 1919 the writer m.oved to Southern California taking up 

 work with the Chaffey Junior College of Agriculture. It was found in 

 looking over peaches that were coming into local canneries at Ontario' 

 that quite a large percentage of them, showed injury sim.ilar to that which 

 had been noted in Placer County. Estimates were made of the per- 

 centage of fruit which had the distinct m.arks of thrips and it was decided 

 that at least twenty-five percent of all the fruit which was handled by 

 two large local canneries showed marked infestation. Most of the 

 growers and men associated with the canneries were undecided as to what 

 had caused the injur}-. A few of the older growers however, recognized 

 the fact that thrips were responsible for this injury- as from time to time in 

 past years they had suffered losses from it. 



In 1920 the writer had an opportunity to inake more extensive ob- 

 servations than previously; these during a }-ear when the pest was 

 worse than it had ever been known in the history of peach growing in 

 Southern California. The loss, while it could not be estimated acciir- 

 ately during this season, would represent a large sum of money. It was 

 estimated by careful observations in the field and of the fruit as it 

 came into the canneries that more than fifty percent showed injury 



