Three Nearctic and six Palearctic populations of Delia radicum L., two Palearctic populations of D. antiqua Meigen, and one Palearctic population of D. floralis Fallen were used to evaluate the range of intraspecific variation in the chorionic ultrastructures of the egg of D. radium, and to compare the chorionic ultrastructures of these eggs with those of the two other species. High variability in the mean size of the egg and hatching slit were found among populations of D. radicum. The D. radicum populations observed were not homogenous for quantitative variables but the qualitative variables showed less variability. Two patterns of antimicropylar poles were observed for D. radicum: the Random and Flower patterns. These two patterns were observed in all Nearctic populations and, among the Palearctic populations, only in the French and the English populations. The other Palearctic populations had only the Random or the Flower pattern. These results support the hypothesis that the North American populations originated from north–western Europe. Our results demonstrate that the three species, D. radicum, D. floralis (Fallen), and D. antiqua (Meigen), have specific chorion, micropyle, and antimicropyle patterns. The eggshell of D. radicum is more similar to that of D. floralis than that of D. antiqua.