130 



DECIDUOUS FEITIT INSECTS AND INSECTICIDES. 



Table XVII. — Larvae of the first brood — Variations in the length of the larval life in the 



cocoon. 



Number 

 of larvae. 



Post- 

 larval 

 stage. 



Number 

 of larvae. 



Post- 

 larval 

 stage. 



Number 

 of larvae. 



Post- 

 larval 

 stage. 



Number 

 of larvae. 



Post- 

 larval 

 stage. 



3 

 2 

 12 

 11 



38 

 7 

 4 



12 



Days. 

 2 

 3 

 4 

 5 

 6 

 7 

 8 

 9 



1 

 3 

 3 

 3 

 4 

 2 

 1 

 1 



Days. 

 10 

 11 

 13 

 16 

 17 

 18 

 19 

 20 



2 

 3 

 3 

 2 

 1 

 2 

 4 

 3 



Days. 

 21 

 22 

 23 

 25 

 26 

 27 

 29 

 30 



1 

 1 

 1 

 1 



1 

 1 

 1 



Days. 

 31 

 36 

 39 

 39 

 40 

 41 

 50 



From Table XVII it will be seen that the average larval life in the 

 cocoon was 11.7 days, the maximum 50 and the minimum 2 days. 

 The average post-larval stage is considerably longer than given by 

 either Mr. Jenne 1 in Arkansas in 1908 or by Mr. Hammar 2 in Penn- 

 sylvania in 1909, in their studies of the codling moth. The former 

 obtained an average of 7.2 days, a maximum of 19 days, and a mini- 

 mum of 3 days, while the latter obtained an average of 7.09 days, a 

 maximum of 19 days, and a minimum of 3 days. 



FIRST BROOD OP PUP.E. 



Time of pupation. — The first pupae observed in the field were col- 

 lected from under the bands on June 6 and from then on weekly to 

 August 15. The first pupa observed in the cages was on June 25 

 and the last on August 20. Pupae appeared in maximum numbers 

 in the cages throughout the month of July. Considering the date of 

 the emergence of the last moth on September 22 and subtracting 

 the average length of the pupal stage, the date of the last larva pupat- 

 ing must have been about September 3. 



Length of the first-brood pupal stage.— The larvae upon which the 

 pupal records are based were collected from banded trees in 1910. 

 One collection was made June 10 of 46 larvae and one June 20 of 95 

 larvae, making a total of 141. In the first collections 11 larvae were 

 males and 35 females and in the second 27 individuals were males and 

 68 females. The sex of the larvae was determined in the same man- 

 ner as was that of the overwintering larvae. (See p. 122.) 



Table XVIII shows a detailed record of the 38 male larvae which 

 had an average pupal stage of 19.5 days; Table XIX shows a detailed 

 record of the 102 female larvae which had an average pupal stage of 

 18.8 days. From records of the overwintering larvae and similar 

 records for 1911 it was apparent that female larvae required a longer 

 pupal period. The above record seems to contradict the other 

 records as 68 female larvae, or 66 per cent of the total number of 



1 U. S. Dept. Agr., Bur. Ent, Bui. 80, Part I. 2 U. S. Dept. Agr., Bur. Ent., Bui. 80, Part VI. 



