Choristoneura rosaceana (Harris)
Adult wings are beige, tinged with red. Forewings are crossed with oblique brown bands (A). The female is larger than the male. The green eggs are laid in masses on the upper surface of leaves (B). The larva is yellowish green to olive green; its head and thoracic shield vary from tan to brown or blackish (C).
Southern Canada and most fruit-growing states in eastern North America.
Attacks apple mainly and occasionally pear, peach, and cherry. Larvae feed on the epidermis of fruit (D), often close to the peduncle or where two apples are in contact; they roll up leaves and hide in these shelters (E). Injuries occurring early in the season cause pronounced deformations of the fruit and are impossible to differentiate from the damage of green fruitworms. Late season fruit feeding causes small pits in the surface (F) that may go undetected until after long-term storage, during which time necrosis can occur.
The fruittree leafroller (Archips argyrospila) and threelined leafroller, Pandemis limitata (Robinson) (G, H) have the same general appearance, but cause few problems. Occasional fruit damage (I) is found in proximity to maple stands and other deciduous forests.
Monitor the adults with pheromone traps and use a degree-day developmental model to time insecticide sprays. Thinning of fruit and pruning water sprouts in midsummer is helpful in reducing fruit damage. These insects may be difficult to control with insecticides, even with selective insecticides (Bacillus thuringiensis and insect growth regulators). Selective pesticides will preserve important natural enemies. More than one spray may be needed during the summer because of this species' extended flight and egg-laying periods.
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