In order to establish a year round indoor-rearing system for Copper butterflies; large copper butterfly, Lycaena dispar, the effect of temperature on larval development and diapause was investigated. Temperature has been suggested as an important factor regulating the developmental rate, length of life, and survival rate from insect. As temperature increased, the developmental period was gradually shorten. The developmental periods of large copper larvae had a range of 11.0 days to 28.5 days at 30℃ and 17.5℃ respectively. The highest emergence rate was 94.2% recorded at 20℃. And the low emergence rate was 72.7% under 17.5℃. We investgated the sensitive stages to diapause induction in the larger copper effect of temperature and photoperiod. The experiment involves transfer of individuals from diapause averting (LD 16:8h, 25℃) to diapause inducing condition (LD 8:16h, 20℃) at various stages. Diapause 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 diapause induction increase with the length of short days and low temperature experienced. The main stage sensitive to photoperiod and temperature induction of diapause determination is the early first larval instar. The diapause induction began 14 days and ended 20 days after hatching larvae (LD 8:16h, 20℃).