Bogong Moth

Agrotis infusa is a nocturnal insect of the family Noctuidae, recognisable by its mottled brown-grey forewings spanning roughly 4-5 centimetres. Adults undertake one of the most remarkable migrations known among insects, travelling up to 1,000 kilometres each spring from breeding grounds in inland Australia to cool alpine caves and rock crevices, where they aestivate in dense clusters through summer before returning to lowlands to breed and die. This mass movement makes the species a critical seasonal food source for alpine predators, including the endangered mountain pygmy possum, and its larvae, cutworms, play a role as agricultural pests and prey within lowland farming ecosystems.

Historically found across southeastern Australia, with the alpine regions of New South Wales and Victoria serving as key aggregation sites, the species depends on both fertile lowland breeding habitat and stable, cool cave microclimates for survival.

Population numbers have declined sharply in recent years, driven by prolonged drought reducing larval food plants and soil moisture needed for breeding, agricultural land conversion and pesticide use in cropping regions, altered fire regimes affecting vegetation, and disruption of temperature and humidity conditions in aestivation caves linked to shifting climate patterns. Light pollution and changing land use further affect migratory navigation and habitat continuity.

Conservation responses include monitoring of aggregation sites, research into migration ecology and climate resilience, and habitat protection measures within alpine national parks. Collaborative tracking programs involving citizen science have improved understanding of population fluctuations.

The species' outlook remains uncertain, with continued reliance on climatic conditions in breeding and aestivation habitats. Population trends currently indicate ongoing decline.