Some biological parameters of the parasitoid, Encyrtus aurantii (Geoffroy) (Hymenoptera : Encyrtidae) were studied under controlled laboratory conditions at five levels of temperature 18, 21, 24, 27, and 30 °C, 65±5% R.H. and a photoperiod of 16:8 (L:D) h when reared on Brown soft scale Coccus hesperidum L. (Homoptera: Coccidae) reared on Pumpkin Cucurbita moschata during the season 2010- 2011 . Result showed that the longer developmental period from egg to pupa was on 18 °C with an average of 24.25 days, and the lower developmental period was on 30°C with an average of 8.25 days. The longer developmental period from pupa to adult was on 18 °C with an average of 10.75 days, and the lower period was on 30 °C with an average of 5.5 days. The lower developmental threshold (LDT) from egg to pupa was 15.83°C, and 14.34°C from pupa to adult. E. aurantii required a Sum of Effective Temperatures (SET) of 122.74 degree-days above the lower developmental threshold (16.95 °C) to complete the development from egg to adult.