Lightbrown apple moth - Life cycle

The life cycle of lightbrown apple moth (LBAM) is different in different parts of New Zealand. Lightbrown apple moth passes through three generations annually in the central New Zealand region, with a partial fourth generation in some years, and has no winter resting stage. There is considerable overlap in the generations, especially in late summer, although development is driven by temperature. In northern New Zealand four overlapping generations are completed annually, with major flight periods occurring during September-October, December-January, February-March, and April-May. In Canterbury, and particularly in Otago and Southland, the number of complete generations is reduced to two, with a partial third generation in some seasons, due to the cooler climatic conditions.

In central regions, adults produced by the overwintering larval generation emerge during October and November (November/January in the south). Eggs are laid in clusters of 3-150 on the upper surface of leaves, and take 8 days at 20° to hatch (longer at cooler temperatures). These give rise to the first summer generation, in which final instar larvae mature between January and mid-February (January to March in the south). Second generation larvae reach maturity during March and April, and the adults from this generation provide third generation eggs in central regions. Normally, the rate of larval development is slowed considerably during the winter; thus the majority of larvae over-winter in the prolonged early juvenile phases of the second, third, and fourth instars. During this period they normally feed on herbaceous plants, although some feed on the buds of deciduous trees and shrubs. Re-invasion of apple trees takes place during October-December, when moths from the overwintered generation start laying eggs again on the apple leaves.