The oleander mealybug, Paracoccus burnerae (Brain), is a pest of citrus in South Africa. This study was carried out to determine the effect of temperature on development rate of P. burnerae and to investigate whether development rate may explain why P. burnerae is outcompeting the citrus mealybug, Planococcus citri (Risso), in the Eastern and Western Cape Provinces of South Africa. The influence of temperature on life history traits of P. burnerae was determined at 20, 22, 25 and 27 °C and compared with corresponding data for P. citri from other studies. The rate of development increased linearly with an increase in rearing temperature in the embryonic, first instar and pupal stages but reached a climax at 26.13 and 28.6 °C in the second instar of both species, respectively. Planococcus citri exhibited lower developmental thresholds except in the first instar, shorter degree-days and faster developmental rates than P. burnerae. Results of the current study indicate that the dominance of oleander mealybug over the citrus mealybug is linked neither to developmental rates nor sum of effective temperatures.