Emergence of cabbage root flies from puparia collected throughout northern Europe

The patterns of cabbage root fly emergence throughout the mainland of northern Europe were equally as variable as those recorded in the United Kingdom. Only the populations from Denmark were as early-emerging as the Wellesbourne flies. In the remaining populations between 15% and 91% of the individuals emerged early. The greatest difference in a continental country occurred in Switzerland where 32% of the flies emerged early at Lausanne, compared to 91% at Wadenswil. These data indicate that forecasting the times of cabbage root fly attack in continental Europe from the accumulation of D° above a base temperature of 6°C will require the same type of extensive data that is currently being collected in the United Kingdom.