Developmental rates, thermal thresholds and thermal requirements for whiteflies, Bemisia tabaci (Genn.) and Bemisia argentifolii (Perring) were studied in relation to temperature and host plants under field conditions. Both species showed a variable response to temperature as indicated from their developmental parameters and thermoliability coefficients. Some plant hosts (cucumber and zucchini) enhanced whitefly development more than the others (cotton and tomato), however B. argentifolii achieved better developmental rates on the tested host plants. Prediction models were, also constructed using three different methods i.e., linear (x-intercept) and non-linear (logistic and algorithm) to simulate the temperature--development relationship of both species on different host plants.