THE CODLING MOTH IN MICHIGAN. 



71 



The time of the emergence of the earliest moths has closely fol- 

 lowed the time of blossoming of apples and occurred from 5 to 10 

 days after the blossoms dropped (Baldwin apples). By adding 

 to these figures the time of flight of the moths previous to oviposi- 

 tion and the time of incubation of the eggs it was found that fully 

 three weeks elapsed before the hatching of the earliest larval of the 

 first brood. 



In 1909 the moths commenced to appear at a normal time, but 

 were somewhat delayed in reaching a maximum of emergence. The 

 season as a whole was fairly normal. The late fall, together with 



Fig. 21.— Diagram showing time ol emergence and relative abundance of spring-brood and summer-brood 

 codling moths, and blooming period of apple trees, during 1909, 1910, and 1911 at Douglas, Mich. 

 (Original.) 



other favorable influences, produced a development of a very large 

 second brood of larvae. Of the total number of larva 1 for the year, 

 43 per cent were of the first brood and 57 per cent of the second 

 brood. This occurrence was perhaps directly due to the unusual 

 rate of emergence of the moths of the summer brood. These com- 

 menced to appear at the normal time, but already reached a maxi- 

 mum during the early part of August (fig. 21) instead of the Latter 

 part of the month, which is the general tendency as shown for 1910. 

 In the band-record curves of figure 22 is shown a corresponding 

 rate in the time of maturity of larvrc of the second brood. The 

 maximum in the first brood of larvae occurred comparatively late, 



