10 



BULLETIN 252, TJ. S. DEPARTMENT OF AGRICULTURE. 



FIRST BROOD OF LARVAE. 



Time of hatching. — The earliest first-brood larvae hatched July 1; 

 the latest hatched August 9. Hence larvae of the first brood were 

 hatching for a period of over one month. The larvae were hatching 

 in large numbers from July 7 to July 15. reaching the maximum on 

 July 13, at which time 1,055 larvae hatched. These records appear 

 in Table VI. 



Length of the feeding period of the transforming larvse. — Three 

 methods for determining the feeding period of the first-brood larvae 

 were used: 



(A) Stock-jar method. The newly hatched larvae were allowed to 

 enter fruit known to be free from codling-moth infestation. This fruit 

 was placed in cages similar to cage e (PL II, fig. 1). As each larva 

 left the fruit its number was recorded upon the cocooning rack 

 directly beneath the cocoon made by the larva. Since the time of 

 entering the fruit was known, the length of the feeding period was thus 

 established. 



(B) Watered stock-jar method. 'This method was similar to (A), 

 except that twigs having two or three apples were placed for a period 

 of two weeks in glass jars containing water. The apples were then 

 pulled and kept under conditions identical with (A). 



(C) Bagged-fruit method. Newly hatched larvae were placed on 

 fruit growing on the tree and the fruit was then covered with per- 

 forated paper bags. After a period of two weeks the fruit was re- 

 moved to the laboratory and kept under conditions identical with (A). 



In 1913 the number of transforming larvae reared at the laboratory 

 was 3.8 per cent of the first brood. All larvae which do not transform 

 during the same season as hatched winter as larvae and pupate the 

 following spring and are designated spring pupae. 



In Table VII the length of the feeding period of the transforming 

 larvae of the first brood (stock-jar method) is given. The average 

 number of days of feeding (male and female larvae) was 20.454; male 

 larvae, 22.333; female larvae, 20.200; maximum feeding period, male, 

 24 days; female, 24 days; minimum feeding period, male, 21 days; 

 female, 17 days. 



Table VII. — Length of feeding period of transforming larvae of the first brood, stock-jar 

 method, Winthrop, Me., 19 IS. 



No. of 

 observa- 

 tion. 



Date of— 



Sex of 

 larva. 



Days of 

 feeding. 



No. of 



Date of — 



Sex of Days of 

 larva, feeding. 



Hatch- 

 ing. 



Leaving 

 fruit. 



observa- 

 tion. 



Hatch- 

 ing. 



Leaving 

 fruit. 



2 

 3 

 4 

 5 

 6 



July 6 

 July 7 

 July 7 

 July 7 

 July 7 

 July 7 



Julv 30 

 July 25 

 July 26 

 July 27 

 July 28 

 July 29 



(7 



e' 



24 



18 l 



19 ! 



20 1 



21 J 



22 ! 



7 

 8 

 9 

 10 



11 



Julv 7 

 Julv 10 

 July 10 

 July 15 

 July 19 



Julv 31 

 July 30 

 Julv 31 

 Aug. 3 

 Aug. 5 



9 24 

 ? 20 

 9 1 21 



IS 8 



Average length of feeding period, male and female larvse, 20.454 days; male, 22.333 days; female, 20.20 

 days. 

 Maximum length of feeding period, mala and female larvse, 24 days; male, 24 days; female, 24 days. 

 Minimum length of feeding period, male and female larvae, 17 days; male, 21 days; female 17 days. 



