24 



DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



LIFE CYCLE OF THE FIRST GENERATION. 



From the earliest appearing eggs in spring, about April 15, to the 

 first appearing moths, June 17, gives some 63 days as the approxi- 

 mate length of the life cycle of the first generation. The laboratory 

 records for individuals kept in breeding cages give a life cycle of 71 

 to 78 days. This, however, is based on only 12 individuals, which 

 completed the cycle, and are recorded in Table VI. Careful obser- 

 vation indicates the length of time of the first generation to be from 

 60 to 70 days. 



THE SECOND GENERATION. 



SECOND-BROOD EGGS. 



Time of oviposition. — A number of moths which emerged at the 

 laboratory in late June and early July were put in rearing cages con- 

 taining small branches of fruit and leaves and also fruit juices and 

 sugar for food. The first eggs were deposited July 3. Some of the 

 moths died before depositing eggs. On June 28, 1909, while looking 

 after spraying operations in the field, frequent searches were made 

 in the unsprayed block, but no eggs were found. During another 

 search on July 7 among these trees many eggs were found and 5 

 larvae just hatched, none of which had entered fruit, were found dur- 

 ing the forenoon. Eggs were being deposited in large numbers in 

 rearing cages July 8 to 10. 



Incubation period. — The time required for incubation was less than 

 half that required for the first-brood eggs. In cages this varied from 

 7 j to 9| days, and averaged 8 J days. The weather at this time was 

 usually warm throughout the day with comparatively cool nights. 

 In Table VIII are recorded incubation periods for several groups of 

 eggs deposited between July 3 and 29. It will be noticed that eggs 

 deposited July 10, 11, 26, and 28 required shorter time for incubation 

 than others. Both of these periods were followed by 3 to 4 days of 

 very warm weather. 



Table VIII. — Incubation periods 



of second-brood eggs, Walnut Creek, Cal., 



1909. 





Number 

 of eggs. 



Date of — 



Period 

 of in- 

 cuba- 

 tion. 



Observa- 

 tion No. 



Number 

 of eggs. 



Date of— 



Period 



Observa- 

 tion No. 



Egg dep- 

 osition 

 (night). 



Hatch- 

 ing of 

 eggs. 



Egg dep- 

 osition 

 (night). 



Hatch- 

 ing of 



eggs. 



of in- 

 cuba- 

 tion. 



1 



3 

 4 

 4 

 10 

 15 

 19 

 15 

 14 

 11 



July 3 



6 



7 



7 



8 



10 



11 



12 



13 



July 12 

 16 

 16 

 16 

 17 

 18 

 19 

 22 

 23 



Days. 



8 

 9 

 8 

 8 

 8 

 7 

 7 

 9 

 9 



10 



45 

 35 

 20 

 12 

 70 

 75 

 60 

 40 

 9 



July 15 

 16 

 17 

 20 

 24 

 26 

 28 

 29 



Aug. 1 



July 24 



25 



26 



29 



Aug. 2 



3 



5 



6 



12 



Days. 



8 



2.. 



11 



12 '. 



8 



3 



8 



4 



13 



14 



8 



5 



8 



6 



15 



7 



7 .. 



16 



7 



8 .. 



17 



8 



9 



18 



10 









Incubation period : Days. 



Average 8. 05 



Maximum 10. 00 



Minimum 7. 00 



