ABSTRACT
Populations of late-emerging cabbage root flies occur quite commonly throughout northern Europe. Instead of emerging at the expected time during late-April and early-May, these populations usually emerge over a protracted period during June and July, It seems likely that late-emerging cabbage root flies have a different type of diapause to early-emerging flies. Investigations are now in progress to determine both the thermal requirements for development of these flies and the factors regulating their late-emergence. Additional studies are also being carried out to develop a suitable chemical method for the rapid identification of late-emerging populations.
