The effect of different temperatures on some biological properties of Nephus includens Kirsch (Coleoptera: Coccinellidae) was investigated. This species is one of the most important predators of Planococcus citri Risso (Homoptera: Pseudococcidae). The development time, mortality and fecundity were determined at constant temperatures of 15, 20, 25, 30, and 35 degreesC and at the variable temperatures, 25-35 degreesC (12 hours 25 degreesC, 12 hours 35 degreesC). Life tables were also constructed for 25, 30, 35, and 25-35 degreesC. The mortality was lower and the mean generation time was shorter at 30 degreesC than at all other temperatures except 35 degreesC. The intrinsic rate of increase was the highest at 30 degreesC (0.081), followed by 0.076 at 25-35 degreesC. The net reproductive rate was higher at 25-35 degreesC than at 30 degreesC. From biological data and population growth parameters calculated from the life tables, 30 degreesC and 25-35 degreesC were determined to be the most suitable temperatures for mass rearing of Nephus includens. However, mass rearing at a temperature as high as 35 degreesC could cause deterioration of sprouted potatoes on which the citrus mealybug is reared. Therefore, 30 degreesC would be better than 25-35 degreesC.