Developmental rates of post-diapause eggs of Diabrotica virgifera virgifera LeConte were compared in the laboratory at six constant temperatures, 12, 16, 20, 24, 28, and 32°C. Linear and nonlinear models were fitted to temperature versus developmental data and were used to predict egg hatch in the field. A four-parameter model fitted to median developmental rates (r2 = 0.99) indicated that development was linear between 16 and 28°C, optimal at 28°C, and decreased at 32°C. The lower development threshold (± SE) (10.5 ± 0.1°C) was determined by linear regression and the x-intercept method. Completion of post-diapause egg development required 258 ± 3 degree-days (± SE) above the base temperature. This compared well with the mean degree-days accumulated to 50% hatch (± SE) of 265 ± 24 which we observed in the field at several locations over 3 years using a degree-day model incorporating an 11°C developmental threshold and soil temperatures at 5- and 10-cm depths. A stochastic simulation model, incorporating a nonlinear developmental function dependant on soil temperatures taken every 2 h also predicted 50% hatch within 2 days. This model was validated in the field with 19 independent records of soil temperatures for several locations at two depths in the soil over 3 years. The simulation model accurately predicted time of 5 and 95% hatch, which indicates that this model has broad application in predicting the pattern of egg hatch for pest management.