Three years of data describing boll weevil overwintering survival, spring emergence, and weather from three locations in the Texas Rolling Plains were used to evaluate a regression model of boll weevil (Anthonomus grandis Boheman) overwintering survival and spring emergence timing and to develop a mechanistic model of the same processes. Criteria for evaluating model performance were (1) the deviation between simulated and observed 75, 90, and 95 percent emergence points in the cumulative emergence, (2) the overall correlation between simulated and observed emergence, and (3) the deviation between simulated and observed overwintering survival. While the first model has worked well, the performance of the second model is significantly better, particularly when the influence of fall food quality is taken into account. We feel the model's overall assumption that spring emergence occurs through two mechanisms, a degree-day accumulation and a reserve depletion, has been verified.