grasses overtake these pastures, conditions are unfavourable for larval survival since larvae do not consume these plants. This leads to delayed breeding, as bogong moths are multivoltine and so can raise multiple generations. Instead, adult bogong moths migrate in a southerly direction during the summer and aestivate (remain dormant), until conditions are favourable again. Aestivation sites During the spring migration, adult bogong moths can be found in their ideal aestivation sites, which generally consist of cool, dark caves and crevices but can include spaces underneath tors and even fallen tree trunks. Stable temperatures and humidity make these locations ideal for bogong moth aestivation. Crevices regulate their environment through wind flow, and caves generally have more regular temperatures and greater humidity. This reduces water loss in bogong moths during their inactivity. While temporary sites can be used in lower elevations, these sites undergo massive population fluctuations and movements throughout their use. Permanent aestivation sites are generally found in higher altitudes of 1500 metres (4920 ft) or above, with the largest, most stable aggregations found on the summits of mountains such as Mt. Gingera. Life cycle Adult bogong moths lay up to 2000 eggs in the soil or on plants near the soil after returning from aestivation sites in the autumn migration. Incubation times vary depending on temperature, with eggs hatching after a period of 4–7 days in laboratory conditions. The larvae of bogong moths undergo six instars. Caterpillars grow slowly throughout the first three instars, taking until June to develop over the winter. However, the larvae go through fast growth during the spring, reaching the final instar in late August to September, soon before migration. They are active at night, when they feed on plants within breeding grounds. Larvae undergo pupation in soil chambers at a depth of 20–150 mm (0.8-7.9 in). Pupation can last between 3–11 weeks depending on the temperature and environment. Pupae are 20 mm (0.8 in) in length and have a shiny, brown appearance. Adults emerge from the soil chambers and shortly after begin migration. Adult bogong moths are active at night, and have different seasonal behaviors. During the spring, bogong moths feed and migrate south, where they aestivate during the summer. Adult bogong moths are not sexually mature yet, and do not actively seek food during this period of dormancy. In autumn, the moths migrate again and return to their breeding grounds, laying eggs and dying.