Eggs are laid in clusters of 3–150 on leaves or fruit. A single female might lay hundreds of eggs. Adults produced by the overwintering larval generation emerge during October and November. These give rise to the first summer generation, in which final instar larvae mature between January and mid February. Second generation larvae reach maturity during March and April, and the adults from this generation provide third generation eggs. Normally, the rate of larval development is slowed considerably during the winter, particularly when temperatures approach freezing; 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. Re-invasion of apple trees takes place during October-December, when moths of the third generation start laying eggs again on apple leaves.
The insect is regarded as an herbivorous generalist, and the larvae feed on numerous horticultural crops in Australia and New Zealand, where they have limited natural predators. It is known to feed on 123 dicotyledonous plant species, including 22 Australian natives, belonging to 55 different families. In New Zealand, over 250 host species have been recorded. It feeds on nearly all types of fruit crops, ornamentals, vegetables, glasshouse crops, and occasionally young pine seedlings.
The larvae cause significant damage to foliage and fruit. Early instars feed on tissue beneath the upper epidermis (surface layer) of leaves, while protected under self-constructed silken webs on the undersurface of leaves. Larger larvae migrate from these positions to construct feeding niches between adjacent leaves, between a leaf and a fruit, in the developing bud, or on a single leaf, where the leaf roll develops. The late stage larvae feed on all leaf tissue except main veins.
Superficial fruit damage is common in apple varieties which form compact fruit clusters, though more significant damage may also occur such that crops are no longer commercially viable. Leaves are webbed to the fruit and feeding injury takes place under the protection of the leaf; or larvae spin up between fruits of a cluster. Internal damage to apple, pear, and citrus fruits is less common, but a young larva may enter the interior of an apple or pear fruit through the calyx or beneath the stem of a citrus fruit. Excreta are usually ejected on to the outside of the fruit.
In sharp contrast to most affected regions, the Hawaii Department of Agriculture says the moth "has not been a significant pest in Hawaii" and finds it beneficial in a few cases, because it kills some invasive plants, including gorse and blackberry.
No one knows how long LBAM has been present in California, though widespread confirmed insect captures have been found across much of the coastal region of the state. After the moth was confirmed for the first time by DNA testing to be present in California in 2007, quarantine measures and a controversial program of aerial spraying proprietary synthetic pheromone pesticides over urban and suburban areas was begun. Other less controversial efforts included nursery and grower treatment of potential infestations in plants using graduated Integrated Pest Management (IPM) techniques with pesticides, smothering oils, and biologic controls such as Bacillus thuringensis. USDA officials obtained an Emergency Exemption from Registration from the U.S. Environmental Protection Agency that allowed them to bypass state rules for the use of pesticides, such as the production of a state-required environmental impact report. Public outcry has been significant, especially after an initial round of aerial spraying, when over 600 complaints of adverse health effects were reported to government agencies and local groups opposing the aerial spraying. Medically documented confirmation of actual effect on health or causation of illness has not been provided by either the claimants nor the state. On June 19, 2008 the State of California announced that it was abandoning plans for aerial spraying over population centers in favor of using local application of pheromone-impregnated twist-ties, a control measure that has proven effective in New Zealand.