THE CODLING MOTH ON PEARS IN CALIFORNIA. 



19 



Walnut Creek, three eggs were found on foliage in the field, and on 

 May 2 eggs were numerous throughout the valley. At Suisun, CaL, 

 larvae were hatching April 29, and on May 3 young larvae were quite 

 numerous in some of the warmer sections of Suisun Valley, indicating 

 that eggs were deposited in numbers some two to three weeks before,, 

 that is, from the 1 2th to the 20th of April. 



Incubation period. — One noticeable difference between the life his- 

 tory of the codling moth in California and in the country east of the 

 Rocky Mountains is the increased length of time required for incubation 

 of the first-brood eggs. As a rule there is considerable cool weather, 

 especially at night, during the months of April and May. This was 

 especially noticeable in the vicinity of Walnut Creek in 1909. The 

 time required for incubation varied from 17 to 22 days, averaging 

 20.05 days for the individuals under observation. The individual 

 record for 56 eggs, deposited from May 8 to 11, are given in Table VI. 



In the spring of 1910 the period of incubation was not observed 

 individually for many eggs, but all indications were that the incuba- 

 tion period varied from a minimum of 15 days to a maximum of over 

 30 days, with the majority requiring about 25 days. 



Table VI. — Life cycle of the first generation, Walnut Creek, CaL, 1909. 





Date of— 





Days for- 







Individ- 

 ual No. 



Egg dep- 

 osition 

 (night). 



Hatch- 

 ing. 



Larva 



leaving 



fruit. 



Pupa- 

 tion. 



Emer- 

 gence of 

 moths. 



Incu- 

 bation. 



Feed- 

 ing of 

 larva. 



Making 

 of co- 

 coon. 



Pupal 

 period. 



Total 



life 



cycle. 



1 



May 8 



8 

 8 

 8 

 8 

 8 

 8 

 8 

 8 

 8 

 8 

 8 

 8 

 8 

 8 

 8 

 8 

 8 

 8 

 8 

 9 

 9 

 9 

 9 

 9 

 9 

 9 

 9 

 9 

 9 

 9 

 9 

 9 

 9 

 9 



May 29 

 29 

 28 

 28 

 28 

 -28 

 28 

 28 

 29 

 28 

 29 

 29 

 29 

 29 

 28 

 30 

 30 

 30 

 26 

 26 

 26 

 27 

 27 

 27 

 28 

 28 

 29 

 27 

 27 

 27 

 27 

 30 

 30 

 29 









21 

 21 

 20 

 20 

 20 

 20 

 20 

 20 

 21 

 20 

 21 

 21 

 21 

 21 

 20 

 22 

 22 

 22 

 18 

 18 

 18 

 18 

 18 

 18 

 19 

 19 

 20 

 18 

 18 

 18 

 18 

 21 

 21 

 20 











2 

















3 

















4 

















5 

















G 



June 24 

 27 

 29 

 29 



July 1 



July 24 



27 

 30 

 32 

 31 



7 



23 



IT 



7 





8 



4 

 5 



25 

 23 



5 

 6 



21 

 18 



7& 



9 



76 



10 





11 



24 

 24 

 29 



2 



18 



26 

 26 

 31 



8 



16 



71 



12 





13 













14 













15 



24 

 24 

 23 







27 

 25 

 24 









16.. 



June 30 

 30 





6 



7 







17 









18 









19 

















20 

















21 



23 



30 



18 



28 



7 



18 



71 



22 





23 

















24 



30 

 29 







34 

 32 









25 



July 6 



21 



7 



15 



73 



26 





27 



July 9 







41 









28 













29 

















30 

















31 



June 26 



5 



21 



30 



9 



16 



73 



32 





33 

















34 



24 







26 









35 













36... 



30 



24 



5 



21 



2i 



25 



ii 



ie 



7$ 



