2 CIRCULAR 2 7 0, U. S. DEPARTMENT OF AGRICULTURE 



INTRODUCTION 



The production of deciduous-tree fruits constitutes one of the im- 

 portant industries of the Pacific Northwest. In recent years the 

 average annual value of these crops produced in Washington and 

 Oregon is said to have been approximately $40,000,000. 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 at least $4,000,000 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 (Carpocapsa 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 all the apple- 

 growing districts of the West, having been accidentally introduced 

 from Europe into the Eastern 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. 

 This poison acts rather slowly, and the worm often makes a small 

 burrow before it dies. Stings range from pin-point size, made by 

 worms that have just succeeded in puncturing the skin, to an eighth 



