72 



BULLETIN 1235, U. S. DEPARTMENT OF AGRICULTURE. 



Table 60. — Percentage of transforming and wintering codling moth larvae, Yakima, 

 Wash., 1919, 1920, and 1921. 



Year. 



Brood. 



Number of larvte — 



Per cent 



trans- 

 forming. 



Per cent 

 winter- 

 ing. 



Leaving 

 fruit. 



Trans- 

 forming. 



Winter- 

 ing. 



1919 

 1920 

 1921 



f First 



173 

 423 



306 

 485 



662 

 589 



147 

 6 



235 



1 



548 

 6 



26 

 417 



71 

 484 



114 

 583 



84.97 

 1.42 



76.80 

 .21 



82.78 

 1.02 



15.03 

 98.58 



23.20 

 99.79 



17.22 

 98.98 



(Second 



f First 



(Second 



/First 



(Second 



NATURAL ENEMIES OF THE CODLING MOTH. 



Natural enemies of the codling moth are conspicuously absent in 

 the Yakima Valley. While collecting larvae from bands, evidences 

 of attack by predacious insects were occasionally observed, and 

 carabid beetles were numerous about the trees, but no beetles were 

 noticed in the act of killing larvae. 



In October, 1919, at Buena, Wash., a small number of codling-moth 

 eggs on harvested apples were found to be infested with a parasite, 

 which upon emergence proved to be Trichogramma minutum Riley. 

 This is the only instance of parasitism observed in these studies. 



In 1914, at Wenatchee, Wash., the senior author collected from 

 cocoons of the codling moth a specimen of an ichneumonid parasite, 

 which was determined by R. A. Cushman, of the Bureau of Entomol- 

 ogy, to be Aenoplex plesiotypus Cush. In 1916, at Wenatchee, two 

 specimens of Aenoplex plesiotypus and one specimen of another 

 ichneumonid parasite, Epiurus indagator Walsh, also determined by 

 R. A. Cushman, were reared from codling-moth cocoons by the senior 

 author. 



Because of the absence of natural enemies of the codling moth in 

 the Yakima Valley, several hundred codling-moth larvae parasitized 

 by Ascogaster carpocapsae Vier. and Bassus carpocapsae Cush. were 

 sent to this laboratory from Dover, Del., by E. R. Selkregg, from 

 Cornelia, Ga., by E. R. Van Leeuwen, and from Sandusky, Ohio, by 

 G. A. Runner, all of the Bureau of Entomology. Many of these 

 succumbed during the extreme cold of December, 1919, and no 

 results were obtained the following year. In 1921 a large number 

 of these parasites were reared and liberated, and evidences of para- 

 sitism were observed in several codling-moth larvae collected under 

 bands in August and September. In June, 1922, two specimens of 

 Bassus carpocapsae were reared from this material, showing that this 

 species is becoming established. These attempts to introduce 

 hymenopterous parasites of the codling moth will be continued. 



REVIEW OF SEASONAL HISTORY OF THE CODLING MOTH IN 1919, 



1920, AND 1921. 



The seasonal history of the codling moth in the Yakima Valley 

 for 1919, 1920, and 1921 is given graphically in Figures 11, 22, and 32. 

 Each curve shows approximately the occurrence of one stage in the 

 development of the insect. A comparison of the seasonal history for 

 the three seasons is given in Table 61. 



