Summary:
The first generation of adult carrot fly emerge from pupae in the soil in the spring, and lay eggs close to the base of vulnerable crops. Larvae initial feed at the surface, then tunnel into the tap root. Adults emerge mid-July and can lead to a second generation. The model determines the start of the flight period for the 1st generation of carrot rust fly based on accumuleted degree-days (260 day-degrees) over a base temperature of 5°C.