The development period of immature stages of the green apple aphid, Aphis pomi (De Geer) (Homoptera: Aphididae), at six constant temperature regimens (20, 24, 28, 30, 32, and 34°C) was modeled to determine mathematical functions for simulating aphid development. Ten models (one linear and nine nonlinear) were used to describe the relationships between temperature and development rate of the different instars and stages of A. pomi (DeGeer) at constant temperatures. All models (except logistic and linear) provided accurate values for the optimum temperature for the first-, second-, third-, and fourth-instar larvae and for total development. The results suggest that, among four models (Hilbert and Logan, Lactin, Briere, and Analytis) that estimate all three parameters (t_min, t_opt, t_max), Lactin and Hilbert and Logan models gave the most suitable fit of data.