SCRAPING AND BANDING FOR CODLING MOTH CONTROL 6 



6 feet from the tree base, was run through a sifting machine (Carlson 

 and Yothers 3) , and the residue was carefully examined for cocooned 

 larvae. The soil below the place where the trash had been removed 

 was also sifted and the residue examined. The number of individuals 

 recovered from the trash or soil was then multiplied by four to obtain 

 the total numbers presumably present under the tree. The results of 

 these studies are summarized in table 1. 



Table 1. — Distribution of overwintering codling moth larvae on 

 apple trees, 1938-1$ 



Treatment of trees in 

 previous years 



Total 

 larvae 



Larvae on or in— 





Larvae 

 per tree 



Trunks 



Scaffold 

 limbs 



Branches 



Trash 



Soil 



Not scraped and 

 banded 



Scraped and banded. _ 



Number 



13, 435 



2,275 



Percent 

 42 

 20 



Percent 

 43 

 21 



Percent 



13 

 50 



Percent 

 1 

 8 



Percent 

 1 

 1 



Number 

 168 

 22 



The larval populations in the trash and soil appear to be of little 

 importance in commercial orchards in the Yakima district. The 

 population on the trees that had been scraped and banded the pre- 

 ceding season or seasons had been markedly reduced by the treatment. 

 On these trees the rough bark had been cleaned off and the trash 

 against the base of the tree cleared away, so that there were few places 

 for the larvae to hide. Consequently, most of them settled in the 

 sheltered spots available on the branches, in pruning wounds, and in 

 the trash on the ground. 



In 46 trees scraped and banded the previous year and examined 

 in the spring before moth emergence, 1,219 codling moth larvae 

 hibernated as follows : 32 percent in rough bark, 22 percent in pruning 

 wounds and broken limbs, 16 percent in crotches, 11 percent in knots, 

 11 percent in trash and soil beneath the trees, and 8 percent in miscel- 

 laneous places. In 37 trees not scraped and banded and examined in 

 the spring before moth emergence, 4,072 larvae hibernated as follows : 

 63 percent in rough bark, 4 percent in pruning wounds and broken 

 limbs, 23 percent in crotches, 3 percent in knots, 4 percent in trash 

 and soil beneath the trees, and 3 percent in miscellaneous places. 



Most of the rough bark had been removed in scraping and the 

 crotches were largely cleaned out ; therefore the percentage of worms 

 in these places was reduced. In all other locations the percentages 

 were greater in scraped and banded trees. The theory that scraping 

 drives a larger proportion of the larvae into the less accessible places, 

 thereby prolonging moth emergence, is substantiated by these figures ; 

 however, although the percentage of larvae driven to these 'locations 

 was greater, no larger numbers were found there. 



The location and type of hibernating places were determined in 

 March, April, and early in May, and do not represent a stationary 

 condition. There is probably considerable variation between fall and 

 spring percentages of larvae in the different locations. Many of the 

 larvae that have spun up in the trash and fruit under the trees and in 

 the soil at the base of the trees, and the more exposed individuals on 

 the trunk, scaffold limbs, and branches had doubtless been destroyed 



