Drosophila circadian rhythm is a daily 24-hour cycle of rest and activity in the fruit flies of the genus Drosophila. The biological process was discovered and is best understood in the species Drosophila melanogaster. Other than normal sleep-wake activity, D. melanogaster has two unique daily behaviours, namely regular vibration (locomotor activity) during the process of hatching (called eclosion) from the pupa, and during mating. Locomotor activity is maximum at dawn and dusk, while eclosion is at dawn.