THE CODLING MOTH ON PEARS IN CALIFORNIA. 25 



SECOND-BROOD LARVAE. 



Time of Thatching . — July 12 was the date of first hatching of larvae 

 at the laboratory. These were from eggs deposited the night of July 

 3. As several adults had emerged and died previous to this date, it 

 was not the actual beginning of the egg-laying period. Second-brood 

 larvae were hatching in numbers July 18 to 20. 



On July 7 careful search in the field showed 5 very young larvae. 

 From July 10 to 12 second-brood larvae were plentiful; from July 15 

 to 18 they were numerous, and by this time their work was showing 

 a great deal on the unsprayed trees. Occasionally 3 and 4 entrance 

 holes were found in a single pear. 



Development oflarvse in relation to fruit. — The first picking of pears 

 in the orchard where the spraying experiment was carried out in 

 1909 began July 15 and lasted 5 days. During this time young 

 larvae were hatching and entering the fruit in numbers in the unsprayed 

 block, so that even the earliest first picking of fruit did not wholly 

 escape the second-brood larvae. In 1910 many second-brood larvae 

 were in the fruit before the first picking. The second and third pick- 

 ings, coming later, are worse injured. The third or last picking 

 receives practically the full force of the second-brood larvae. In many 

 orchards this picking will run 70 per cent wormy. The third picking 

 of pears on the unsprayed block in 1909 showed an average of 75 per 

 cent wormy, while in 1910 practically all of the pears left on the trees 

 in the check blocks were wormy. 



Life oflarvse in fruit.- — The period covered by the life of the larvae 

 in the fruit was not positively determined for a very large number of 

 second-brood larvae. The harvesting of the fruit takes a large per- 

 centage of the larvae to the packing shed before they reach full 

 development. 



At the laboratory several hundred individual records were started, 

 but the quick rotting of some of the fruit during a short absence 

 destroyed part of the records. The first larvae left the fruit August 

 6, 1909, at the laboratory, but in the field comparatively few larvae 

 as a rule reach their full development before the fruit is all harvested, 

 which is about the middle of August. In the summer of 1910 the 

 first full-grown larvae of the second brood were found at Suisun July 

 26, and at Walnut Creek on August 1. At this time practically all 

 pears around Suisun and about two-thirds of the crop in the vicinity 

 of Walnut Creek had been harvested. 



Records for 63 individuals which went through in sound or nearly 

 souRd fruit out-of-doors at the laboratory in 1909 are given in Table 

 IX. As may be seen, this gives about 26 days for the period of the 

 larvae in the fruit. 



