321 



Table II. Method of Calculating the Amount of Development of the Pupa in 

 One Day from Hygrothermograph Records. 



Applying the values from Table I and Fig. 15 to the record for Apr. 13, 2 P. M., 



to Apr. 14, 12 M., 1915 at Olney, 111., as shown in Fig. 1. 



(Record supplied by P. A. Glenn.) 



Temper- 

 ature 



(° F.) 



Humid- 

 ity. 



(%) 



Amount of Development in each 

 two-hour period. 



4 



6 • 



8 ' 



10 • 



12 ■ 



2 A. 



4 



6 • 



s • 



10 ■ 



12 M. 



15.4 



12.8 



10.2 



2.2 



0.0 



0.0 



0.0 



0.0 



0.0 



0.8 



12.2 



16.6 



Total for the 24 hours = 70.2 developmental units. 



Thus, the amount of development of the pupa for that day was 70.2 

 developmental units. To complete the pujsal stage under normal condi- 

 tions requires a total of 6-180 developmental tinits. (Unusually light or 

 unusually heavy rainfall in the preceding autumn requires a larger or a 

 smal'er total for the spring pupa, as shown in Table III.) Thus, if the 

 amount of development is calculated for each day from the beginning of 

 the pupal stage until the sum of developmental units approaches (5180 



T.Mii.E III. Autumn Rainfall Corrections Applicable to the Developmental Total 

 for Spring Pupae, especially first pupations and first maximum. 



(Based on a comparison of Tables VII and VIII with weather data for the 

 periods involved.) 



