Females lay eggs in the growing tips of Cape-ivy vines a day or two after emergence. They lay their eggs in tightly packed bundles in a single vine tip or node, depositing an average of 61 eggs during their lifetime. The presence of larvae triggers the formation of a single-chamber gall in the plant tissue surrounding the larvae. Several larvae often live communally within each gall, feeding on galled plant tissue. Larvae develop through three instars. Just prior to pupation, which occurs within galls, a late third-instar larva chews a passage through the gall wall without puncturing the external cuticle, leaving behind a “window” on the outside of the gall. Following pupation, adult flies break through the window and exit the gall head-first. The entire life cycle requires ~50 days under greenhouse conditions and up to three months or more under field conditions. The life cycle timing is also water and temperature dependent, requiring an additional 1–2 weeks during winter and 1–2 weeks less in summer; insect development is delayed by about one week in water-stressed plants. Drought-induced wilting, as is typical at dry sites in summer, reduces fly gall formation and reproduction. Under laboratory conditions, no overwintering or diapause has been observed. It is estimated there could be up to seven field generations a year in southern California, but likely fewer (2–4) in northern California.