Summary:
Carrot flies (Psila rosae/Chamaepsila rosae) overwinter in the soil either as diapausing pupae or as larvae. Late-developing insects remain as larvae and continue to feed on carrot roots throughout the winter. The model simulates the development of cohorts of 500 individuals through adult emergence, egg laying and hatching. For each stage, the percentage development is calculated each day by integrating the appropriate development rate curve.