Chilocorus bipustulatus (L.) is an important predator of scale insects that is widely distributed in citrus plantations in the Mediterranean Region of Turkey. The developmental time of C. bipustulatus, a polyphagous predator, was studied at six different, constant temperatures (14, 18, 22, 26, 30 and 34 C) and a relative humidity (R.H. of 65+/-1%, with Aspidiotus nerii Bouche (Hemiptera: Diaspididae) as the prey. The developmental periods of immature stages were 61.67, 51.00, 41.21, 33.72, 26.76 and 27.17 days at 14, 18, 22, 26, 30 and 34 degrees C, respectively. The developmental threshold for C. bipustulatus determined with the linear model was 5.91. Linear regression was employed to determine the thermal constant of 651.1 degree-days. In this study linear and nonlinear regression models are discussed.