Spring emergence of the crucifer flea beetle, Phyllotreta cruciferae (Goeze), was investigated in 2003 and 2004 in relation to habitat type, vegetative cover, and soil temperature in the Mixed Grassland Ecoregion of western Canada. Although total emergence extended over 10–12 weeks, emergence patterns were quite similar in both years with limited emergence for several weeks before and after a large emergence peak of comparatively short duration. In each year, peak emergence occurred near the end of May as mean ground temperature reached 15°C. Approximately 45,000 flea beetles were collected with the greatest number of flea beetles recorded from a single 1m 2 emergence cage being 3736. Significantly more flea beetles emerged from sheltered locations than from open habitats; sheltered areas were predominantly shelterbelts and yard sites of Caragana and poplar trees. In each year, highest numbers of flea beetles emerged in cages placed in Caragana while the fewest emerged from cages in grassy areas. Consistently more females than males emerged throughout the spring with a sex ratio of approximately 1.5 females: 1 male. Emergence of new generation adults occurred from the middle of August until the end of September; this emergence was delayed and extended in late-seeded canola. Seeding date and rate did not significantly affect the abundance of new generation flea beetles. The sex ratio of new generation adults was approximately 1.2 females: 1 male. Emergence cages could be a useful tool for researchers monitoring year-to-year populations of P. cruciferae but the narrow time frame between spring emergence and crop infestation may restrict the usefulness of this tool for producers.