Adult females lay eggs in the upper surfaces of leaves, near the leaf margin, producing blister-like swellings. When the larvae hatch, they move to┬áthe underside of the leaf and begin feeding. Early instars feed only on the undersides of leaves, scraping away most tissue, but creating small “windows” by leaving thin, transparent layers. Later instars feed on both lower and upper surfaces of the leaves, avoiding large veins, and they perforate the foliage completely. Mature larvae pupate in cocoons that they spin at the base of the plant. The species has up to six generations per year, and adults are active from mid spring until frost.