The effects of temperature and photoperiod on the larval development and gonad maturation of Leptocarabus kumagaii were studied. Larvae kept under diapause inducing photoperiod (12L-12D) completed their development either when photosperiod was changed to 14L-10D or 16L-8D at 15°C or when they experienced a period of low temperature (5°C) under 12L-12D. Egg production after adult emergence was promoted when photoperiod was changed from 16L-8D to 12L-12D or 14L-10D. At 12L-12D, oviposition started in 10-25 days and continud for 50 days, whereas at 14L-10D it started in 40-50 days and lasted for 150 days. Also, egg production was promoted at lower temperatures of 15 and 20°C but not at a higher temperature of 25°C. Under laboratory conditions, there was no difference in patterns of larval development and gonad maturation among a few local populations at different altitudes showing different seasonal cycles. Direct effects of temperature on the altitudinal variation of the seasonal cycle were suggested.