The second-generation larvae, which develop in late summer and fall, feed primarily on leaves until they enter diapause, although they may occasionally damage fruit. Photo by G. Krawczyk.
The preferred hosts are plants from the family Rosaceae, including apple, peach, and pear. Although historically this leafroller is considered a minor pest in Pennsylvania, multiple outbreaks in various areas are cause for concern.
Description and life cycle
This species is one of the larger leafrollers feeding on tree fruit in Pennsylvania. Adults are ½ inch long with a wingspan of 1 inch. The forewings are light reddish-brown and are crossed by three oblique chocolate brown bands. The hind wings, not visible when the moth is at rest, are pale yellow. Egg masses are laid on the upper surfaces of leaves, are greenish yellow, are about 3∕16 by 3∕8 inches in area, and may contain 200 or more eggs. The black head capsules of embryonic larvae become visible just before they hatch. Newly hatched larvae have a yellowish green body and a black head and thoracic shield. Mature larvae are 1 inch long and distinct from other leafrollers by the combination of either a black or variably brown head and thoracic shield with a green body. Pupae are dark brown, about ½ inch long, and are usually found in rolled leaves on the tree.
Obliquebanded leafroller has two generations per year, overwintering as small larvae in the trees. The overwintering larvae become active when trees break dormancy, and they complete their development about 3 weeks after the apple blossom period. Adults begin to emerge in late May or early June. Females can lay up to 900 eggs during a 7- to 8-day oviposition period. Eggs hatch in about 10 to 12 days. This generation takes almost two months to complete development. Adult flight of the second generation occurs in August, and the larvae hatch in August and September. Young larvae construct hibernation sites on twigs or bark to spend the winter.
This species has three feeding periods during the year. Overwintered larvae feed on developing flower buds and floral parts throughout the blossom period. After petal fall, these larvae continue to feed on developing fruit. Newly hatched first generation (summer) larvae move to and feed on tender growing terminals, watersprouts, or developing fruit. As these larvae reach the third instar, they display an increasing propensity to damage fruit. The second-generation larvae, which develop in late summer and fall, feed primarily on leaves until they enter diapause, although they may occasionally damage fruit.
Monitoring and management
Scout for larval shelters during bloom to petal fall. A petal fall treatment with an insecticide effective on mid-sized to large larvae should control overwintered larvae. The flight of adults can be monitored with pheromone traps. The trap data can establish biofix and estimate the population density. The second window of control is in June/ July, when most summer-brood eggs have hatched.
Since the larvae preferably feed on or inside young growing terminals, it is recommended to repeat insecticide applications if intensive new terminal growth occurs. Specific chemical recommendations for home gardeners are in Fruit Production for the Home Gardener, and recommendations for commercial growers are in the Penn State Tree Fruit Production Guide.