The bogong moth (Agrotis infusa) is a temperate species of night-flying moth, notable for its biannual long-distance seasonal migrations towards and from the Australian Alps, similar to the diurnal monarch butterfly. During the autumn and winter it is found in southern Queensland, western New South Wales, western Victoria, Tasmania and also in South and Western Australia. Adult bogong moths breed and larvae hatch during this period, consuming winter pasture plants during their growth. During the spring, the moths migrate south or east and reside in mountains such as Mount Bogong, where they gregariously aestivate over the summer until their return towards breeding grounds again in the autumn.

The moth's name, bogong, is derived from an Australian Aboriginal language; the Dhudhuroa word bugung describes the brown colouration of the moth. It is an icon of Australian wildlife due to its historical role as an important food source and because Aboriginal peoples would come to where the moths spend the summer to feast on them and hold intertribal gatherings. In recent years, it has been seen in major cities like Canberra, Melbourne, and Sydney due to strong winds during its spring migration.

Starting around 1980 and accelerating rapidly after 2016, the bogong moth population has sharply declined as a result of increasingly severe droughts, along with increased temperatures in caves used by the moths for aestivation, both primarily resulting from anthropogenic climate change. In December 2021 the bogong moth was added to the IUCN Red List as an Endangered Species.

Bogong moths was first described by French lepidopterist Jean Baptiste Boisduval in 1832, who described the moth as Noctua infusa from a type specimen from Australia. He described the moth as having blackish-brown hind wings. However, in 1903 British entomologist George Hampson classified a specimen with white hind wings under this name, alongside another specimen of Agrotis spina with blackish-brown hind wings. Australian amateur entomologist Alfred Jefferis Turner identified A. spina as a synonym of A. infusa in 1920. I. F. B. Common, an Australian entomologist, found specimens with both hind wing colours in 1954. Specimens with the white hind wings were only found during specific months in mercury vapour light traps near Canberra, and he attributed the white hind wing specimens to a seasonal form.

The moth's name, bogong, is derived from the Dhudhuroa word bugung, meaning brown moth. Its presence has contributed to the naming of numerous locations and landmarks. For example, a town, Bogong, in the Australian state of Victoria has been named after the moth. Mount Bogong, located south of the Bogong High Plains, is also named after the moth, with its traditional name, Warkwoolowler, meaning the mountain where Aboriginal people collected the "boo.gong fly". The Taungurung name for the bogong moth is debera.

In the Australian state of New South Wales, a series of mountains in the Kosciuszko National Park are named the Bogong Peaks.

Adult bogong moths have an overall dark brown colouration, with a dark stripe interrupted by two light-coloured spots on the wings, distinguishing it from other moths. There are visual differences between the migratory and nonmigratory forms of the moth; migratory moths have brown hind wings while nonmigratory moths have paler hind wings. Bogong moths have a wingspan ranging between 40–50 mm (1.6-2.0 in), and a body length of around 25–35 mm (1-1.4 in). The average weight of an adult bogong moth is 0.326 grams.

Bogong moth eggs are dome–shaped in appearance and are vertically ridged. They are 0.7 mm (0.03 in) in diameter and 0.4 mm (0.02 in) in height.