Biology
Adult moth’s forewings are pale-green or yellow-green; hind wings are brownish-gray to grayish; both wings have a white, frayed outer edge. The wingspan is approximately 18 to 23 mm. The head is yellowish and adults have a grayish, 8 mm long abdomen. Larva: Younger larvae are gray coloured with dark heads. Older instar larvae turn gray-green. Larvae are 15 to 19 mm long and 2.5 mm wide. Egg: Eggs are round, with a diameter of about 0.7 mm. They are initially light yellow, later changing to brown. Each female oviposits approximately 50 to 60 eggs in pairs within a cement-like mass. Eggs are deposited on branches, leaves, and branch forks, within the entire crown. A dust and algae lining make the eggs nearly invisible.
Nature of Damage
Emerging larvae bore into open buds, since closed buds cannot be penetrated. Therefore, emerging larvae can only survive if the buds are in synchrony with their development. As the buds flush, the larvae move to young leaves and flowers and continue feeding. Larvae construct shelters by rolling leaves with silk webbing Third instar larvae become more mobile and are thus more visible. Similar to other tortricids, when larvae are disturbed, they will drop on a silken thread. Last instar larvae feed upon the expanded foliage as well as the bark of tender young shoots. Tortrix viridanais part of a Quercus dieback complex that results in thinning foliage, progressive die-back, cambial necrosis, epicormic shoot development and tree mortality. Successive defoliation can cause growth loss and can also weaken trees and predispose them to mortality by other organisms (Canadian food inspection agency).
Monitoring
Russell IPM manufactures and supplies pheromone lure – the Qlure, traps and complete monitoring systems for Tortrix viridana, Green Oak Moth.
Pheromone trap data gives early warning of the infestation and will also alert the user to a low level of population before it becomes serious.
The lure can be best applied with the Mothcatcher trap or Delta trap.
