The mealy plum aphid, Hyalopterus pruni (Geoffroy) (Hemiptera: Aphididae) is a serious insect pest of apricot trees in Egypt. The impact of aphids as pests is well characterized by their population growth rate, a parameter integrating their age-specific development, survivorship, and fecundity. These population parameters were measured at three constant temperatures on potted apricot seedlings (small trees 2-yr old). The developmental threshold temperature was greater for the nonlinear model than for the linear model. The greatest proportional survivorship of nymphs occurred at 25 ºC., mean daily fecundity was lowest at 30 ºC and highest at 20 ºC. The adult longevity decreased with temperature. The population growth rates for H. pruni were estimated as fecundity and development time and were the highest at 20 ºC. The obtained results were documented the temperature dependence of the life history parameters for H. pruni and generate a degree-day model for the prediction of phonological events.