Predictive models were developed to forecast the emergence of female blueberry maggot flies in highbush blueberries. Time to emergence at 20°C for pupal samples transferred from outdoors late February through mid-March, in 1997 and 1998, was very similar, suggesting both diapause completion and minimal postdiapause development at this time. Linear and nonlinear models were fitted to postdiapause development rates at several constant temperatures (7, 11, 15, 20, 25, and 30°C). The low temperature development threshold for the linear model was estimated at 4.7°C, and the heat accumulation required for median emergence was 934.3 degree-days. Rate summation was initiated on 1 March, over 3 yr, and model predictions were validated with field emergence data. The linear model predicted emergence with an average error of <4 d of observed field emergence, for percentiles at and below the median, over a 3-yr period, compared with 4.0–5.4 d for the nonlinear biophysical model. The results of this study indicate that a simple linear model, driven by soil temperatures, can assist the monitoring of blueberry maggot fly in integrated pest management programs.