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Oriental fruit moth

Grapholita molesta (Busck)
Lepidoptera: Tortricidae

The adult is a small moth with dark gray mottled wings that lighten somewhat at the outer edges (A). The larva is dirty white to pinkish with a reddish brown head and an anal comb (B).

Distribution

Widespread and a major pest in ON, QC and most fruit-growing states in eastern North America.

Damage

Attacks all deciduous fruits, particularly peach and apple. On peach, larvae feed first on new terminal growth, tunnelling toward the base of the shoot, causing the terminal to wilt and die back (called "shoot flagging") (C); this damage may be confused with that caused by periodical cicada oviposition, which also can cause terminal wilt. Later broods attack and tunnel in the developing fruit, causing conspicuous entrance or exit holes covered with frass (D), while the larva excavates cavities near the pit. On apple, terminal feeding is similar to peach but less obvious; feeding damage in the fruit (E) is random and often marked by frass near the calyx.

Similar Species

Larvae resemble those of the codling moth (Cydia pomonella), which does not possess an anal comb, and (in apple) tends to damage the seeds as well as the fruit flesh. Larvae also resemble those of the lesser appleworm (Grapholita prunivora), which also possesses an anal comb but is somewhat smaller than G. molesta. A stronger resemblance to the cherry fruitworm (G. packardi) is more difficult to resolve, although that species usually does not attack apple. Lesser appleworm larvae tend to retain their pinkish color when boiled and preserved in alcohol, as compared with the latter two species.

Management

This insect historically has been the major internal worm pest in commercial peaches, and is becoming a more serious pest in apples as well. Monitor adults with pheromone traps and use a degree-day developmental model to time insecticide sprays. Summer applications of insecticides, such as those used in apples against codling moth, can provide control of this insect. Success has been achieved using mating disruption alone (especially in area-wide programs) or, under heavy population pressure, in combination with insecticide sprays.

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