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IPM Methods:  Determining Treatment Timing Using Degree Days and Insect Phenology Models


Degree days (DD) are a measurement of heat units over time, calculated from daily maximum and minimum temperatures.  Degree days are used to predict insect life cycles, and in turn, time insecticide treatments to those life cycles.  Insects are exothermic (“cold-blooded”) and their body temperature and growth are affected by their surrounding temperature.  Every insect requires a consistent amount of heat accumulation to reach certain life stages, such as egg hatch or adult flight.  Degree days interpret that heat accumulation.