In order to establish an indoor-rearing system for Copper butterflies; Large Copper butterfly, Lycaena dispar, the effect of temperature, photoperiod on larval development was investigated. As temperature increased, the developmental period was gradually reduced. The developmental periods of Large Copper larvae was 11.0 days and 28.5 days at 30℃ and 17.5℃, respectively. We investigated the sensitivity of stages to diapause induction. The experiment involved transfer of individuals from diapause averting (LD 16:8 h, 25℃) to diapause inducing condition (LD 8:16 h, 20℃) at various stages. Daipause was induced in 95.2% insect transferred at hatching larvae, in 15.6% of insects transferred at 2nd stadium molt, in 0% of insects transferred at after 3rd stadium molt. Percentage of diapause induction increased with the length of short days and low temperature. The main sensitive stage to photoperiodic and temperature induction of diapause determination was the early first larval instar. The diapause sensitivity began 14 days and ended 20 days after hatching larvae. The main stage sensitive to photoperiodic induction of diapause determination was the early first larval instar under low temperature and short day length. In relation to diapause termination, pupation was accelerated with cold treatment after diapausing 15 to 20 days and suitable chilling temperature was 8℃.