III. SWD Development Introduction
SWD development (phenology) is estimated using degree-day models to predict seasonal development by the different stages in the life cycle of SWD (egg, larvae, pupae, and adults). These models give a general idea of when SWD begins spring egg-laying and how many generations per year develop, but the models are not very precise and should always be used in conjunction with field monitoring data. Always use caution in the interpretation and application of these models.