none Microplitis croceipes entered diapause in response to short daylengths under experimental photoperiodic conditions. Critical daylengths of 10.5:13.5 (L:D) at 21 degree C and 11:13 (L:D) at 18 degree C were demonstrated. The development of the M. croceipes egg/larvae represented the sensitive period, and the responsive stage was the prepupa. A significant interaction was shown between photoperiod and temperature in diapause induction. High variability was shown in development times from cocoon formation to adult emergence. Temperature alone (15 degree C) induced 100% diapause in a long photoperiod of 14:10 (L:D).