108 



DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



that its development has been greatly influenced by the temperature. 

 A cold spell was invariably followed by a delay in transformation, 

 while a rise in temperature produced a corresponding hastening in 

 development. 



COMPARATIVE LIFE-HISTORY STUDIES FOR THE SEASONS OF 



1907, 1908, AND 1909. 



On considering the records of the emergence of the moths (tig. 31) 

 and the time of maturity and relative abundance of larvae (fig. 32) 

 for the three years under consideration, it is evident that the codling 

 moth in its development is greatly influenced by seasonal conditions. 



MAY 



JUNE! 



JULY 



AUG. 



SEPT. 



15 20 E5 3 



1 5 10 15 10 25 3 



5 10 15 20 25 3 



1 5 io 15 10 25 3 



1 5 10 15 Z0 









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Fig. 31.— Time of emergence of spring-brood and first-brood moths, and the blossom periods of apple 

 trees, during 1907, 190S, and 1909, at North East, Pa. (Original.) 



The cold and wet spring of 1907 limited the emergence of the spring 

 moths to a short period. The prevailing low temperature delayed 

 the larvae to such an extent that only 3 per cent of the first brood 

 transformed. The entire second generation was reduced to 3.5 per 

 cent against 96.5 per cent of the first generation. 



The season of 1908 was evidently very favorable for the develop- 

 ment of the codling moth. The early spring brought out the moths 

 by May 25. During the long and warm summer the majority of the 

 larvae of the first brood transformed in great numbers (only 32.3 per 

 cent wintered), and the following brood of larvae attained a size equal 

 to that of the first brood. 



