4 CIRCULAR 8 2 8, U. S. DEPARTMENT OF AGRICULTURE 



by birds and rodents. The larvae that had not been disturbed by 

 spring were the ones found and recorded in these studies. 



Many larvae were also found in such places as rotten spots on trees, 

 empty sacks, papers, old clothes, broken boxes, spliced tree props, dried 

 fungus growths on the trees, under birds' nests, and in canker wounds. 



PERCENTAGE OF LARVAE REMOVED BY SCRAPING 



Eight Jonathan and six Winesap trees in three orchards were 

 scraped in the regular manner, and the scrapings were examined for 

 larvae. On the Jonathan trees 82 percent of the larvae were removed 

 by scraping, and on the Winesap trees 77 percent. Afterward the 

 trees were carefully examined for larvae that had been missed or were 

 inaccessible. Throughout moth emergence the trees were examined 

 for empty pupal cases. The Jonathan variety, because of the absence of 

 cracks, holes, and sprout clusters, lends itself more readily to thorough 

 scraping than do the Winesap, the Delicious, and certain other 

 varieties. 



In a single study of four Jonathan trees that had been scraped the 

 previous season, only 50 percent of the larvae were removed. Appar- 

 ently, after the first scraping, the larvae were forced into the more 

 inaccessible situations and therefore were not so readily removed by a 

 later scraping. 



PROPORTION OF LARVAE CAUGHT IN BANDS AFTER 

 LEAVING THE FRUIT 



The proportion of the larvae that leave the fruit and are captured 

 in chemically treated bands depends on the variety, age, and size of 

 the trees. The number of larvae caught depends on surface charac- 

 teristics, such as roughness of the trunk and scaffold limbs after 

 scraping, the number of cracks, knot holes, broken limbs, and crotches 

 inaccessible to scraping, as well as the thoroughness of scraping and 

 the fit of the bands. 



Two methods of making such determinations were employed. In 

 each method the trees were first carefully scraped and banded, about 

 the middle of June, with regular corrugated-paper beta-naphthol 

 bands. In one method all the dropped and harvested wormy fruit 

 \\ as cut open and examined, the dropped fruit being examined every 

 30 days and both dropped and wormy fruit at harvesttime, and the 

 number of exit holes was recorded. At the same time, or a few days 

 later, the bands on these trees were removed and examined for the 

 total number of larvae caught. The final results of these tests on four 

 leading commercial varieties over a period of 7 years in several 

 orchards, are given in table 2. There was considerable variation in the 

 percentage of larvae captured, both for years and varieties. 



The other method differed from the foregoing in that, starting 

 about July 10, and ending at harvesttime, all apples on each tree and 

 the dropped fruits on the ground were examined every 30 days for 

 exit holes. Each exit hole for each tree was recorded, and on the same 

 dates the bands were removed and the number of larvae caught was 

 also recorded. New bands were then placed, since those examined 

 were unfit for replacement. After the harvest examination of the 

 fruit, the bands were usually allowed to remain for a few days, to allow 



