Overwintering adults emerge and feed on leaves and young shoot buds in early spring as soon as purple loosestrife shoots emerge. After mating, females lay up to 400 eggs in groups of 2–10 on stems and leaves from late spring through summer. Eggs hatch after about one week, and larvae move to leaf buds, where they remain well concealed as they feed. There are three larval instars. Older larvae openly feed on leaves and developing inflorescences. Mature larvae move into the soil or litter beneath purple loosestrife plants to pupate. On flooded purple loosestrife, pupation occurs in the spongy tissue (called aerenchyma) that develops on flooded portions of the stem. Development time from egg to adult is 30–40 days. New adults emerge in early summer, resume feeding, and then overwinter in plant litter. Both species usually have only one generation each year, but a partial or even complete second generation may occur depending on annual climate variation and latitude. If a second generation develops, new adults may emerge as late as the end of August. Adult loosestrife beetles are very good fliers, and they can easily find new patches of purple loosestrife on which to feed and reproduce. Loosestrife beetle adults are known to disperse 2–5 miles (3.2–9.0 km) a year on average.