ECONOMIC ZOOLOGY — ENTOMOLOGY. 155 



far the most destructive of tlie two, both by reason of its numbers and because 

 of the stage of the fruit when it appears. 



In 1909 the first pupa was found on March 11. Four of 300 larvfe collected 

 from banded trees during February, 1910, had pupated by March 12. Of the 

 118 which produced adults in the spring, 95 had pupated by March 31 and all 

 had pupated by April 10. The time spent in the pupal stage is said to vary 

 considerably for different individuals, but all of this brood in 1909 required a 

 month or more, the average time being 39.54 days. It is thought probable that 

 in 1909 the first adult api^eared about March 23, as on this date an apparently 

 freshly-shod pupal skin was found and another was discovered in the field 

 on March 27, at which time Bartlett pears were just about in full bloom. In 

 the spring of 1910, moths were seen in the orchard April 9, although none 

 emerged at the laboratory until April 14. The period of emergence of moths is 

 said to last about 2 months. 



In 1909 no eggs were laid in the breeding cages until May 7. although many 

 were found in the orchard on May 5. Since practically all moths in the field 

 had emerged by May 0, it is thought improbable that any eggs were deposited 

 in the field after May 15. In 1910 several eggs were found on foliage in the field 

 April 25 at Walnut Creek and on May 2 eggs were numerous throughout the 

 Valley. 



One noticeable difference between the life history 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, due to the fact 

 that as a rule there is considerable cool weather, especially at night, during the 

 months of April and :May. 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. A limited number of observations in 1910 indi- 

 cated that the incubation period varied from a minimum of 15 to a maximum of 

 over 30 days, the majority requiring about 25 days. 



The first larva under observation in 1909 hatched out May 7 from eggs col- 

 lected in the field. On ^lay 11, 1909, a number of recently hatched larvfe were 

 found in the orchard, while on May 11, 1910, young larvfe were quite numerous 

 in the field. Of the larvje hatching under observation in 1909, only 29 reached 

 full development in the fruit, from 25 to 42 days being required. " The first 

 larva to leave the fruit in the field was not observed, but on June 5, 3 newly- 

 formed pupae and 20 full-grown larvae were found under bands on 21 pear trees, 

 and 4 pupae and 28 full-grown larvae were found under bands on 10 apple trees. 

 The time from leaving fruit to pupation for this brood, averaging 7 J days, would 

 indicate that the first full-grown larvae left fruit in late May. Band records 

 and data obtained by bringing in quantities of wormy fruit picked from trees 

 in May showed a maximum number of first-brood larvae leaving fruit June 14 

 to 26. However, later-maturing larvae of this brood left fruit as late as July 

 21. In the summer of 1910 many full-grown larvae had left the fruit prior to 

 June 1. At Walnut Creek on June 1, 4 pupae and 248 larvae were taken from the 

 bands on 11 apple trees, and at Suisun on June 3, 10 pupae and 45 larvae were 

 taken from bands on 15 pear trees. The time spent from leaving fruit to pupat- 

 ing varied from 3 to 23 days, with an average of 7i days. . . . The first 

 pupae were found in the field June 5, 1909. when a total of 7 were taken with 

 49 larvae under bands from 21 pear and 10 apple trees. In 1910 pupae were 

 found June 1 and were plentiful in the vicinity of Suisun and Walnut Creek 

 by June 5. . . . Records kept out-of-doors for 165 individuals gave a minimum 

 of 10 days and a maximum of 27 days with an average of 16J days for the time 

 spent in the pupal stage. . . . The total time from leaving fruit to emergence 

 98334°— No. 2—11 5 



