Oriental Fruit Moth
Oriental fruit moth, Grapholita molesta, is a pest of most stone and pome fruits. In pome fruits, its appearance and injury is similar to that of the codling moth and lesser appleworm.
Adults are gray, with a wing spread of 1/4 inch; the wings are gray with brown markings. Eggs are single, flat, whitish ovals on twigs or the undersides of leaves. Larvae are grayish white with a black head and reach 1/2 inch at maturity. Larvae are distinguished from codling moth by the presence of a black anal comb on the top of the last body segment.
Oriental fruit moths have four to five generations per year in Pennsylvania, with the first and last two generations being the most numerous. They overwinter as larvae in silken cocoons on the tree or on the ground, and they pupate and begin to emerge as adults during April, shortly before peach trees bloom. These females lay up to 200 eggs, primarily during May. 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. 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 or to the core. The mature larva exits the fruit from the side leaving a large gumming hole with much frass. In apples, oriental fruit moth larvae may feed around, but not in, the core.
Insecticide spray timing can be aided by using pheromone traps. The sex pheromone traps should be placed in stone fruit and/or apple orchards in early April and checked at least once per week. Broad-spectrum insecticide spray should be applied about 7 days after the beginning of the generation(s) and repeated 7 to 10 days later for each generation. Orchard sanitation also helps--remove dropped fruit and other ground litter that may serve as development and overwintering sites.
Mating disruption (e.g., 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.