6 



BULLETIN 911, U. S. DEPARTMENT OF AGRICULTURE. 



FEEDING PERIOD OF SECOND -BROOD LARV^ IN REARING CAGES. 



Records from the date of hatching to the date of cocooning were 



secured from 51 individuals as shown in Table VI. 



Table VI. — Feeding period of second-brood larvx of the grape-berry moth in rearing cages, 



Sandusky, Ohio, 1916. 



Date of hatching. 



Date of 

 cocoon- 

 ing. 



Number 



of 

 cocoons. 



Feeding 

 period . 



Total. 



Aug. 11 



Do 



Do 



Do 



Aug. 13 



Do 



Do 



Do 



Do 



Do 



Do 



Aug. 16 



Do 



Do 



Do 



Do 



Do 



Do 



Sept. 5 



Sept. 6 



Do 



Total. 



Average 



Maximum.. 

 Minimum.. 



Aug. 31 

 Sept. 1 

 Sept. 6 

 Sept. 7 

 Aug. 31 

 Sept. 1 

 Sept. 2 

 Sept. 4 

 Sept. 7 

 Sept. 9 

 Sept. 10 

 Sept. 1 

 Sept. 4 

 Sept. 9 

 Sept. 10 

 Sept. 11 

 Sept. 12 

 Sept. 14 

 Oct. 11 

 Oct. 9 

 Oct. 12 



Days. 



Days 



40 

 105 

 104 

 27 

 18 

 42 

 22 

 96 

 108 

 58 

 30 

 48 

 95 

 72 

 75 

 78 

 81 

 29 

 36 

 33 

 36 



24.18 



36 



16 



The average length of the feeding period for the 51 larvae was 24.18 

 days, a much shorter period than has previously been recorded as the 

 average for the second brood. This shortening was due no doubt to 

 the unseasonably warm weather that prevailed during August, - 

 September, and early October of 1916. This figure should not be 

 taken as representing the usual condition, but is presented here to show 

 the influence of a warm fall on the maturing of the larvae. The maxi- 

 mum length of the feeding period was 36 days and the mhiimum 16. 



LENGTH OF THE PREPUPAL PERIOD. 

 The length of time between the spinning of the cocoon and pupa- 

 tion was recorded for 13 individuals as shown in Table VII. 



Table VII. — Length of the prepupal period of 13 individuals of the second brood of the 

 grape-berry moth, Sandusky, Ohio, 1916. 



Date of spinning cocoon. 



Number 

 of co- 

 coons. 



Date 

 of pu- 

 pation. 



Number 

 of days 

 in pre- 

 pupa 1 

 stage. 



Total 

 number 

 of days. 



Aug. 31 



1 

 1 



1 

 2 

 5 

 2 

 1 



Sept. 3 

 Sept. 4 



'.'.'.do'.'.'.'. 

 Sept. 5 

 Sept. 6 

 Sept. 8 



3 



4 

 4 

 3 

 4 

 5 

 7 



3 



Do 



4 



Do 



4 



Sept. 1 



6 



Do 



20 



Do 



10 



Do 



7 







Total 



13 





54 











Average length of prepupal period, 4.15 days. 

 Maximum length of prepupal period, 7 days. 

 Minimum length of prepupal period, 3 days. 



