Brownheaded leafroller - Life cycle

The life cycle of brownheaded leafroller is different in different parts of New Zealand and similar to that of lightbrown apple moth. Brownheaded leafroller passes through three generations annually in the central New Zealand region 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 three generations are completed annually, with major flight periods in Auckland hard to distinguish because of the continuous overlapping of generations. In Canterbury, the number of complete generations is reduced to two due to the cooler climatic conditions. Brownheaded leafroller also completes two generations in Otago (at the same time as greenheaded leafroller flights) but this species occurs at extremely low levels in apple orchards, even though common on other host plants.

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 2-216 on the upper surface of leaves, and take about 9 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. In the north of the North Island, flights of adults occur during the winter, which is warmer than further south.