Grape Berry Moth
Grape berry moths feed on grapes, both cultivated and wild species. They prefer tender skinned varieties with tight fruit clusters.
Damage is caused by the larvae feeding in flowers and fruit. Small fruit, when damaged, turn dark purple in color and drop from the stems. Larger fruits are usually webbed into the cluster and shrivel or rot in place.
This insect overwinters in the pupal stage in its cocoon. The larva forms its cocoon by cutting out a small piece of leaf and folding it over to form a cavity which it lines with silk. The cocoon is connected with the leaf at each end by a small, uncut piece of leaf tissue. The leaf folds containing the cocoons may remain attached to the leaves or may break off and fall to the ground. The adults emerge in late spring, about the time grapes bloom (April). Females lay their flattened, circular, cream colored eggs at dusk, on the fruit, stems, flower clusters, or newly forming grape berries. First generation larvae feed on flowers or very young fruit clusters. This early activity is relatively unimportant in most vineyards. Later generations feed on developing or ripening grapes, often webbing several fruits together. Each larva may destroy three or four fruits. Development from deposition of the eggs to emergence of the adults averages about five weeks. There are as many as three generations per year in Oklahoma.
The adult is a small moth with a wingspread of about 3/8 inch. The front wings are brown with a slight purplish sheen. The head is brown, and the center portion of the forewings may appear to have a dark saddle-like band running across them. Young larvae can be either yellowish green or dull white with a black head capsule. Mature larvae range from olive green to brown in color and are about 3/8 inch long. Caterpillars, when disturbed, wiggle and squirm vigorously to escape and will drop to the ground if possible.
Please contact your local county extension office for current information.