The life cycle of the Common Leopard Butterfly Phalanta phalantha phalantha was studied under laboratory conditions (RH 34%, Temp. 28.5ºC) by providing fresh leaves of Rukam Asam Flacourtia montana and in the natural habitat (on plant F. montana) during the winter. The life cycle consists of four life stages: egg, larva (five instars), pupa and adult with an average duration of egg: 4 days, larva: 24 days (laboratory condition) /27 days (natural condition), pupa: (lab. - 8 days and natural- 9 days) and adult: 6 days. The life cycle was completed within 42 (lab. condition) - 46 (natural) days. The fifth instar larval duration was less by 3 days and the pupal stage was less by 1 day under laboratory conditions than natural conditions. The study concluded that climatic factors greatly impact the duration of each life stage in butterflies.