Diapause production of the tobacco hornworm,Manduca sexta(L.), on flue-cured tobacco in North Carolina is examined and quantified. The resultant simulation model uses an ovipositional preference matrix constructed from egg counts on various phenological states in experimental field plots in different areas. The model considers foliage consumption of the pest species and the effect of parasitization on host feeding. It requires host plant data inputs, provides damage information, and predicts potentially overwintering populations as related to existing cultural practices and hypothetical situations meaningful in developing long-term management strategies.