CODLING MOTH IN SANTA CLARA VALLEY. 119 



SEASONAL-HISTORY STUDIES OF 1910. 

 SPRING BROOD OF PUPJE. 



Time of pupation. — The earliest pupation observed during the 

 spring of 1910 in the breeding jars was on March 3 and the latest 

 pupation April 25. Considering the time when the first adult 

 emerged on March 30, and adding the average length of the pupal 

 stage, or 40.7 days, the earliest pupation must have taken place 

 about February 18. As the latest adult of the spring brood of moths 

 emerged on June 9, the last overwintering larvae must have pupated 

 about May 1. 



Pupae were therefore in evidence from February 18 to June 9, a 

 period of 111 days. 



Figure 29 shows when the first, last, and maximum pupation took 

 place in the rearing cages, as well as the daily mean temperature, and 



Fig. 29.— Diagram showing time of pupation of spring brood of pupae, 1910. (Original.) 



that the overwintering larvse pupated from March 3 until April 25. 

 Most of the larvse pupated during the period from March 8 to 25. 



An examination of figure 29 shows that the sudden increase hi daily 

 mean temperature after February 20 probably started overwintering 

 larvse pupating. The high daily mean temperature from March 8 

 to 20 explains the maximum time of pupation, and shows that a drop 

 or increase of 5 degrees in mean temperature usually influenced 

 accordingly the number of larvae pupating. The period of low mean 

 temperature from March 20 to 27 stopped pupation to some extent, 

 but it was started again hi the remaining days of March and in early 

 April. By tins time practically all of the larvse had pupated, and the 

 warm period following has no bearing on the time of pupation. 



