62 Journal of Agricultural Research voi. xiii, no. i 



type found in some cherries. In slender shoots, such as peach, three, 

 four, or five tips usually will be killed before the larva has matured 

 (PI. 5, A) Another type of twig injury is found on peach in late summer 

 and fall after the tvngs have hardened and stopped growing and after 

 the fruit is gone. This is found usually at the site of previous attack 

 where the gum has exuded and adhered to the bark, sticking fast dead 

 leaves and other debris (PI. 5, B). In this mass the larva starts work, 

 causing more sap to exude and the twig to swell and in some cases to 

 develop a gall-like formation. The larva mines in the bark and wood of 

 such a twig usually until ready to spin a cocoon. The first six or eight 

 buds below the terminal also may be injured by the late-working larvae. 

 The amount of twig injury varies considerably on difiterent food 

 plants, the peach coming first in severity of attack. Young cherries 

 of a number of varieties and the varieties of flowering cherry are very 

 severely injured. Quince probably comes next in the list of injured 

 plants, with plum, apple, pear, nectarine, and apricot following. 



FRUIT INJURY 



Injury is first noticed in peaches about the time the fruit is the size 

 of chestnuts or slightly larger. In other fruits it has not been noticed 

 so soon. The early injury is caused by larvae of the second genera- 

 tion, the first-brood larvae confining themselves almost entirely to the 

 twigs while the fruit is yet small. The second-brood larvae begin work- 

 ing in the twigs, but when about half grown a few of them turn their 

 attention to the fruit. They bore into the side of the peach (PI. 6, 

 A, B) and tunnel through the fruit until they are fully developed, 

 emerging sometimes at the point of entrance but most generally through 

 another hole. Such injury usually does not cause the peach to rot or 

 fall to the ground while the fruit is green and hard, but the sap exudes 

 from the wound in the peach, forming a smear of gum on the outside. 

 Frequently the larva, after making a hole in a peach, is apparently 

 "drowned out" by the sap. The sap continues to flow, causing the 

 same gummy appearance of the peach as though the insect had con- 

 tinued to work in the fruit. Most of the third-brood larvae begin work 

 in the twigs in the same way as the previous broods. A few, however, 

 attack the peach as soon as they are hatched. At this time the early 

 midseason varieties of peaches are ripening and the insect finds it easier 

 to gain entrance to the fruit than when it is green. In a few days nearly 

 all of the insects of this brood desert the twigs for the fruit, and it is at 

 this time that the severe injury to the fruit begins. Varieties of peaches 

 ripening after the ist of August are all subject to severe injury. 



The spot on the fruit most often selected as a point of entry is the 

 area surrounding the stem. When the fruit is beginning to soften the 

 larvae work beneath the skin at this point and go directly to the seed, 

 leaving in many cases no sign that they have entered. Sometimes, 



