Flea beetle eggs are tiny, (0.4 mm or 1/20 in.), elongated, and yellow. The larvae are a dirty-white colour with brown heads. When mature, the larvae are slender, up to 6 mm (1/4 in.) long, with 3 pairs of short legs on the thorax. The pupae are white and about 2.4 mm (1/8 in.) in length.
The adult beetles are small, blackish beetles with a metallic or bright blue lustre, measuring about 2-3 mm (1/8 in.) in length. Some species are striped; others plain.
After mating and egg laying in early June, the overwintered adults begin to die off. The young larvae feed on the roots of the developing canola for three to four weeks. They are present from about mid-June to late July.
After feeding, the larvae form earthen cells in which they pupate. The new adult flea beetles begin emerging in late July and early August. These adults feed on the green tissue of suitable host plants that are still present. Feeding may continue into mid-October. However, by mid-September, most adults have usually entered a dormant, overwintering stage. Only one generation of flea beetles is produced each year.