Fruit ripens earlier than usual. Shriveled, hollow berries lie on the soil beneath the plants. Berries still on the plants have small, crescent-shaped slits in the skin. Inside are smooth, legless, yellowish-white grubs with brown heads.
Once the fruit is infested, you cannot kill the grubs inside. Pick and destroy the infested fruit. The following spring, spray the plants with an insecticide labeled for plum curculio.