The importance of directed movement by adults of the onion maggot, Delia antiqua (Meigen), in the colonization of new onion fields was assessed. In two mark-recapture experiments where flies were released in the center of circular bands of onions or nonhost vegetation, recaptures of mated females in the host and nonhost circle were distributed randomly. Recaptures of males were distributed randomly in the nonhost circle and directionally in the host circle, either downwind (release 1) or upwind (release 2) of the release point. In six similar releases in two nonhost environments, recaptures of females were randomly distributed regardless of mating status. Recaptures of males were often significantly directional but not correlated with wind direction. Mating status and ovarian development of feral D. antiqua trapped at three sites with different cropping histories were measured. Ovarian development and mating status of flies recaptured in nonhost vegetation 1.2 km from the nearest onion field or overwintering site were similar to those trapped in an onion field. Flies trapped at an overwintering site with no host plants were, on average, younger and less likely to be mated. These results suggest that long-range directed movement has little influence on the probability or extent of colonization of new onion fieldsby D. antiqua .