The larva, which is the stage of this insect's lifecycle that causes the actual damage to the fruit, is similar to a typical fly larva or maggot. Female flies lay eggs in the cherries, where the larvae feed for 1–2 weeks before exiting. Western cherry fruit flies damage fruit by feeding, in both the adult and larval stages.
This insect's juvenile stage, which causes actual damage to the fruit, is comparable to that of a typical fly or maggot. Female flies lay eggs inside cherries, where the larvae feed for 1–2 weeks before leaving. Western cherry fruit flies harm fruit through feeding, both in their adult and larval stages.