CIRCULAR 270, U.S. DEPARTMENT OF AGRICULTURE 



of the total for the United States. The average value over the 5-year 

 period 1926-30 was about $59,000,000. The annual loss due to 

 insects in the United States, including the actual loss of fruit and the 

 cost of combating the insects, has been conservatively estimated at 

 10 percent of the value of the crop. This does not seem too high for 

 the Pacific Northwest, and it is thus apparent that insects take an 

 annual toll of nearly $6,000,000 from the fruit growers in this region. 

 This circular gives information about the most important insects 

 found in the orchards of Oregon, Washington, Idaho, and western 

 Montana. 



APPLE AND PEAR INSECTS 

 CODLING MOTH 



No insect causes greater loss to apple and pear growers in the 

 Pacific Northwest than does the codling moth (Carpoeapsa pomonella 

 L.). Individual growers may lose more than 50 percent of the crop, 

 but by using proper control methods they could usually keep the 



losses below 5 percent. 

 The codling moth 

 occurs in practically 

 all the apple-growing 

 districts of the West, 

 having been acciden- 

 tally introduced from 

 Europe into the East- 

 ern States and thence 

 transmitted to the 

 Pacific coast. 



NATURE OF INJURY 



The larva or worm 

 is the only injurious 

 stage of the codling 

 moth, and the only 

 injury of consequence 

 is to the fruit. The 

 young worms, upon 

 hatching from the eggs, crawl to the nearest fruit and burrow 

 into it, producing the familiar wormy apple or pear. Many worms 

 enter through the calyx end, where the calyx affords them protection 

 and they can easily obtain a foothold. Many others enter at the 

 point where two fruits touch, or where a leaf is in contact with a 

 fruit. Still others are able to burrow into the exposed side of the 

 fruit. The worm penetrates the skin and excavates a small cavity 

 beneath it in an hour or so. It remains near the surface for a few 

 days and then burrows to the center of the fruit, usually feeding 

 chiefly on the seeds and core. When full grown the worm makes a 

 large tunnel to the surface through which it leaves the fruit. Wormy 

 fruit is of small commercial value > since it will not keep long, and the 

 laws of some States forbid its being shipped, except to byproducts 

 plants. 



A form of injury other than the tunneling is the " sting" (fig. 1), 

 caused by a worm that started to burrow into the fruit and then 

 died, usually as the result of feeding on poison spray on the fruit. 





Figure 1.— "Stings" produced by codling-moth worms on apple. 



