On apples, plum curculio is considered the second most damaging pest after codling moth. Symptoms and Diagnosis Plum curculio beetles, Conotrachelus nenuphar, can be found on plum, cherry, peach, and apple trees as well as nectarine and pear trees. Fruit may fall prematurely, in late May and June. The skin of infected fruit has small crescent-shaped blemished that eventually become swollen and knotted. Upon closer examination, larvae may be seen feeding near the blemishes.
Infested fruit is often hard and misshapen.
The larvae create holes in the fruit skin when they leave the fruit to pupate. These holes are clean-cut and free of frass or webbing. The have four characteristic humps on their wing covers. Adults may overwinter in the soil or in hedgerows near host trees. These adults emerge from their overwintering sites to feed on trees in early spring.