THE CODLING MOTH IN MICHIGAN. 



11 



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

 mary of Table VI. 



Num- 





Num- 





Num- 





Num- 





ber of 



Pupal 



ber of 



Pupal 



ber of 



Pupal 



ber of 



Pupal 



obser- 



period. 



obser- 



period. 



obser- 



period. 



obser- 



period. 



vations. 





vations. 





vations. 





vations. 







Days. 





Days. 





Days. 





Days. 



2 



10 



1 



19 



2 



27 



1 



35 



1 



13 



1 



20 



6 



28 



1 



42 



5 



14 



3 



21 



7 



29 



1 



46 



6 



15 



2 



22 



25 



30 



1 



59 



3 



16 



2 



23 



12 



31 







3 



17 



7 



25 



4 



32 







2 



18 



7 



26 



1 



34 







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 r ppeared June 13 ; the great majority of moths emerged between 

 June A 8 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. 



Num- 

 ber of 

 moths. 



Date of 



emergence. 



Num- 

 ber of 

 moths. 



Date of 

 emergence. 



Num- 

 ber of 

 moths. 



Date of 

 emergence. 



Num- 

 ber of 

 moths. 



Date of 

 emergence. 



5 



5 



1 



4 



17 



40 



52 



82 



162 



232 



199 



128 



June 13 

 June 14 

 June 15 

 June 16 

 June 17 

 June 18 

 June 19 

 June 20 

 June 21 

 June 22 

 June 23 

 June 24 



59 

 56 

 81 

 36 

 45 

 53 

 33 

 34 

 19 

 9 

 10 

 10 



June 25 

 June 26 

 June 27 

 June 28 

 June 29 

 June 30 

 July 1 

 July 2 

 July 3 

 July 4 

 July 5 

 Julv 6 



7 

 6 

 6 

 

 5 

 8 



6 



....... 



July 7 

 July 8 

 July 9 

 July 10 

 July 11 

 July 12 

 July 13 

 July 14 

 July 15 

 July 16 

 July 17 

 July 18 



2" 



........ 



2" 



July 19 

 July 20 

 July 21 

 July 22 

 July 23 

 July 24 

 July 25 

 July 26 

 July 27 



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 PL 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 



