A physiology-based demographic modelling framework was adapted to model the population dynamics of the life stages of Ceratitis Capitata, the Mediterranean fruit fly. The model was calibrated using the Marquardt-Levenberg algorithm with data collected from the literature on the insect's biodemography as a function of temperature. Model calibration led to the selection of Medfly pre-imaginal stages development and mortality functions showing the highest goodness-of-fit. Lactin-2 function was used to represent the developmental rate of all pre-imaginal stages, Wang-2 function for the mortality rate of the egg and larval stages, and the quadratic function to represent pupal stage mortality. The calibrated model provided the percentage of the population of each life stage to the total population of each Medfly generation and its progression over time. The model was validated by comparing its predicted adult stage peak time with that of field samples of the adult population from different regions in northern and central Egypt, both collected for this research work and derived from published sources. Validation showed that the model needs to be further tuned to allow for improved accuracy in predicting the peak time of the different adult generations. The model was compared to an empirical degree-day model, the PBDM model, which was found to be more accurate.