20 



BULLETIN 1235, U. S. DEPARTMENT OP AGRICULTURE. 



THE THIRD GENERATION. 



No attempt was made to secure eggs from the few second-brood 

 moths that were reared. Hence no data are available for the third 

 generation. 



CODLING-MOTH BAND STUDIES OF 1919. 



Owing to the fact that the Yakima Valley is divided into two 

 parts it was considered advisable to keep band records in one orchard 

 m the upper valley and one in the lower valley. The first orchard 

 was inside the city limits of Yakima, about one-fourth mile from the 

 laboratory, and will be spoken of as the Guthrie orchard. In the 

 lower valley an orchard known as the Walden orchard was selected 

 for banding. This is situated about a mile east of Buena and is at 

 the western edge of a large apple district. It is approximately 15 

 miles southeast of Yakima. 



In both orchards burlap bands made of strips of burlap 18 inches 

 wide folded to three thicknesses were applied to the trunks of certain 

 trees and held in place with wire finishing nails. The loose bark had 

 previously been thoroughly scraped from the trees. These bands 

 were examined every three days throughout the season, and the 

 worms found were counted and put into glass jars, where they were 



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OUNE UULY rtVS. S£FT. OCT. 



Fig. 9.— Occurrence of codling moth larvae under bands of apple trees at Yakima, Wash., 1919. 



allowed to spin cocoons in strips of corrugated pasteboard, the moths 

 emerging from these cocoons being used in subsequent life-history 

 studies. 



In the Guthrie orchard the trees were large, being 25 years old or 

 older. These trees were sprayed, but not efficiently enough to con- 

 trol the worms. Twenty-four trees were banded, and a total of 

 2,162 larvae were collected. In Figure 9 will be found the details of 

 these band collections. A distinct break between the first and sec- 

 ond broods will be noted, occurring during the first week in August. 

 The maximum for the first brood was 74 larvae collected on August 1, 

 but it is believed that the true maximum is more nearly represented 

 by the high point of July 17, since the maximum number of larvae 

 left the fruit in the insectary on July 12. The maximum period of 

 leaving fruit for the second brood occurred August 28 to September 

 3, and was September 3 at the insectary. A second high point 

 occurred September 18. This was caused by the cool weather of 

 September 3 to 12 slowing up the growth of the larvae. As soon as 

 the weather became warm again they left the fruit in large numbers. 



The trees in the Walden orchard at Buena were 25 years old. 

 Ten trees were banded, seven of them being sprayed and three un- 

 sprayed. A total of 5,044 worms was collected from these bands, 

 2,021 being from the seven sprayed trees and 3,023 from the three 



