Oriental Fruit Moth
The oriental fruit moth (OFM), Grapholita molesta, is a pest of most stone and pome fruits. On pome fruits, its appearance and injury is similar to that of the codling moth.
Adults are gray, with a wingspread of 1/2 inch; the wings are gray with brown markings. Larvae are grayish white with a black head and are 1/2 inch long when fully grown. OFM larvae have a black "anal comb" on the top of the last body segment, distinguishing them from codling moth larvae. The presence of legs distinguishes them from plum curculio larvae. Oriental fruit moth attack the fruit in much the same manner as the codling moth attacks the apple. Several generations of fruit moths are produced each year, but the first generation is the most numerous. They overwinter as larvae in silken cocoons on the tree or on the ground, pupate in April, and begin to emerge as adults during late April, shortly before fruit trees bloom. Most of the eggs (up to 200 per female) are laid during May as single, flat, whitish ovals on twigs or the undersides of leaves. The succeeding overlapping generations extend into September and October.
The earliest indication of injury is a dying back of the new growth of twigs in spring. This is especially noticeable in stone fruit. A first-generation larva enters at a leaf axil near the tip of a shoot and bores down the central core for several inches, causing the terminal to wilt, or "flag." Later-generation larvae may enter the fruit near the stem end and make feeding burrows that usually extend to the pit. The mature larva exits the fruit from the side, leaving a large gumming hole with much frass.
Spray timing can be aided by using a pheromone trap. Hang traps in early April and check them weekly. To affect the exposed egg-laying females and eggs, apply sprays after the peak of the male trap catch. Orchard sanitation also helps, through the removal of dropped fruit and other ground litter that can act as development or overwintering sites.
Mating disruption (i.e., attract-and-kill Last Call OFM) can be used to manage this pest. Pheromone and insecticide solution droplets should be placed in the mid to upper level of the tree canopy at the label rate at pink stage of apples and again at about every 45 days. The droplets remain effective for at least 6 to 7 weeks. Moreover, monitoring should proceed as usual to check the effectiveness of disruption.