The apple curculio is very small insect feeding on the fruit of apple tree. The apple curculio is brown in color but appears black when seen by naked eye.
They emerge in April into orchards where they starts mating. Egg laying starts from April till mid June. The larva stays in the same cavity where the egg was laid and do not make tunnels into the fruit. The larva gets matured in 3-4 weeks and starts chewing the fruit by making the tunnel into the fruit. Fully grown larvae are light yellow to white in color. Larvae after chewing the fruit drop down and enter into soil where it pupates. After a month adults emerge from the pupa stage.
They attack many types of fruits including apples, plums, peaches, pears and cherries. Adults feed on young fruit injuring the tissue and making the surface hard. When females lay their eggs they chew the outer skin of the fruit and make a cavity to lay their eggs. At harvest, the curculio egg laying scar is visible as a russetted area on the surface of the apple. As the fruit mature the deformation of the fruit increases. Late summer fruit feeding damage appears as irregularly shaped holes that do not have time to heal before harvest. Feeding holes are often on the blossom or calyx end of the apple. Infested fruit may drop prematurely or may be present at harvest making the fruit unmarketable.
There are many natural enemies such as birds and other parasites. Destroy the fruit which are found to be damaged as larva may be present inside the fruit. Remove alternative food or breeding hosts from areas near orchards. An insecticide spray can be made shortly after petals fall from the blossoms or at the first sign of damage. For a high degree of control, a second application can be made about ten days later. If cool weather occurs, a third application may be needed when a high level of control is desired. Contact insecticides applied during early petal-fall will control apple curculio.