The oriental fruit moth (Grapholita molesta) is an important pest of peach and nectarines; other fruit trees like apple, pear, almond and apricot are also attacked by this pest. It is native to north-west China, and spread from Japan to Australia, central Europe, the east coast of the USA and Brazil at the beginning of the twentieth century. Since then, the pest has been introduced into many other countries.
Life cycle and appearance of Oriental fruit moth
The adult has a wing span of 10-16 mm, and is dark-grey. When at rest, the wings are held in a roof-like position over the body, and the antennae are bent backwards over the wings.
Eggs are translucent-white when first laid, later becoming yellow, round or slightly oval, measuring about 0.7 mm across. The full-grown larva has a length of approximately 12 mm, and is pink to almost red. The head and the anal plate are brown. They have a black anal fork (anal comb) above the anal opening.
The cocoon is a protective covering for the full-grown larva and pupa. It is made of silken threads and particles of the objects on which it rests. The pupa is reddish-brown.
The number of generations per year varies according to climatic conditions. In Europe, adults appear from March onwards. Eggs are laid singly on leaves and twigs of trees. The larvae emerge 1-4 weeks later depending on temperature, and bore into buds and shoots. They are fully grown within 2-3 weeks and pupate in a white cocoon spun on the surface of the host plant or under bark. The adults emerge after 1-2 weeks. There are up to five generations per year. The larvae of the later generations feed within developing fruits. Fully grown larvae of the last generation overwinter in cocoons and pupate the next spring.
Infested fruits have frass-filled holes on the surface. On peach, the larvae destroy buds in spring and disrupt the growth of young shoots, causing them to wilt. Infested young fruit may drop prematurely. Attack of older fruits cause distortion. The pulp is partially destroyed and filled with brown frass.