THE CODLING MOTH IN MICHIGAN. 



11 



Table VII. — Length of pupal stage of the spring brood, Douglas, Mich., 1910; sum- 

 mary of Table VI. 



SPRING BROOD OF MOTHS. 



Time of emergence (fig. 6, p. 12). — Notwithstanding the changeable 

 weather conditions during the spring of 1910 the codling moths 

 emerged with striking uniformity. The earliest moth in the rearing 

 cages appeared June 13 ; the great majority of moths emerged between 

 June 18 and June 30; isolated moths continued to appear up to the 

 close of July, when the first moths of the summer brood commenced 

 to issue. The maximum emergence took place June 22. The emer- 

 gence for the spring brood is given in Table VIII. 



Table VIII. — Time of emergence of the spring brood of moths during 1910, at Douglas, 



Mich. 



Variation in size of moths of the spring brood. — The moths of the 

 spring brood vary considerably in size and to a greater extent than 

 do those of the summer brood. (See PI. I, fig. 1.) This might be 

 expected on considering the difference in size of the wintering larvae 

 from which the moths result. 



There have often appeared dwarfed specimens of moths from the 

 band-record material which at first sight could hardly be recognized to 

 be of the codling-moth species. That there should exist a correspond- 

 ing difference in the vitality of individual moths is only natural and is 

 fully reflected in many of the results of the rearing experiments. In 

 view of the great variability in behavior of the insect it has been 

 necessary to conduct many of the experiments on a large scale in 

 order to establish reliable averages. 

 35215°— Bull. 115, pt 1—12 2 



