345 



3LE IX. Showing ttic calculated and actual time for incubation of eggs from 



first generation moths at Olney, III., (1915 J. 

 For detailed explanations see Table VII. 



Fig. 3. Length of the pupal stage of first-generation codling mollis in 1915, 

 1916, and 1917 at Olney, expressed in per cent of standard average time for the 

 stage (scales at the left). The data are plotted for groups of 30 individuals 

 on dates midway between the first pupation and the last emergence of each 

 group. The cross at the left indicates the date of pupation of the first indi- 

 vidual of the first group in each year, and the cross at the right indicates the 

 date of emergence of the last individual of the last group. The mean temper- 

 ature for each day for the whole period covered in each year is plotted accord- 

 ing to the Fahrenheit scales at the right, for comparison with pupation graphs. 

 The inches of rainfall and number of rainy days for each month from the pre- 

 ceding September to and including April are plotted below, with names of 

 months at the bottom of the figure. 



