U. S. D. A., B. E. Bui. 115, Part III. D. F. I. I., Issued January 18, 1913. 



PAPERS ON DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



LIFE HISTORY OF THE CODLING MOTH IN THE SANTA 

 CLARA VALLEY OF CALIFORNIA. 



By P. R. Jones and W. M. Davidson, 



Engaged in Deciduous Fruit Insect Investigations. 



INTRODUCTION. 



The codling moth in California presents so many differences in 

 life history hi comparison with that which has been learned in the 

 East, as well as so many local conditions associated with each particu- 

 lar valley in this State, that there has been felt the need of a more 

 comprehensive study of its life history with the temperature condi- 

 tions influencing the same. 



The data presented in this paper have been collected during the 

 past three years, 1909, 1910, and 1911, only partial records being 

 obtained for the first year but fairly complete notes for the latter two. 



The Santa Clara Valley is practically one large deciduous-fruit 

 orchard from 60,000 to 70,000 acres in extent, hung between the Santa 

 Cruz Range of mountains on the west and the Mount Hamilton Range 

 on the east and extending from the San Francisco Bay just north of 

 Alviso 50 to 60 miles south past the town of Gilroy. The valley 

 varies in width from 5 to 20 miles. 



According to the United States Weather Bureau the average 

 mean temperature for the whole year in this region is 58.1° F., com- 

 piled from a record of 36 years. The annual mean precipitation 

 for this time has been 14.79 inches, with practically all of the rain- 

 fall in January. February. March. Xovember, and December. It will 

 thus be seen that the codling moth is influenced by a low dry mean 

 temperature with little or no rainfall during the period it is attack- 

 ing the fruit. 



The data for 1909 were gathered by Messrs. Dudley Moulton. for- 

 merly of this bureau, and J. R. Horton of this bureau; that of 1910 

 and 1911 by Mr. F. L. Young, formerly of this bureau, and by both 

 of the authors. Miss Emma Weber has contributed many life-history 



observations also during the vears 1910 and 1911. 



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