Newly hatched larvae of grape berry moth feed on the blossoms and young berry clusters externally but when berries are formed they burrow into grape berries and feed internally. In case of heavy infestation, characteristic silver webbing around larvae, bloom and berry clusters are noticed. Also, grape berries injured by larvae can be infected by other pathogens like Botrytis spp and sour rots. These berries can be also invaded by fruit flies, wasps and ants.
Grape berry moth develop through four life stages including eggs, larvae, pupae and adults (moths). Grape berry moth overwinter as pupae in the leaf litter in vineyards. Adult moths emerge from pupae just before the grape bloom. After mating, female moths lay eggs on the clusters near the bloom. These eggs hatch within 3 days into small larvae that keep feeding on the young berry clusters externally and when berries are formed they feed internally on berries until they mature. This first generation mature larvae then pupate in the folded leaves. Adult moths emerge from pupae within 10- 15 days in August. These adults lay next generation eggs from July through September on the berries. Second generation, newly hatched larvae burrow into the grapes, feed internally and mature. Matured larvae then drop off on the ground and pupates in the leaf litter for overwintering and life cycle continues. Under favourable conditions, grape berry moth can complete 2-5 generations in a year.