Description

The two species we have found of the greatest concern is the Queensland fruit fly( Bactrocera tryoni) and the cucumber fruit fly (Bactrocera cucumis). The adults have brown bodies with yellow markings. The house fruit fly (Drosophila melanogaster), also called vinegar fly, which hangs around ripe and decaying fruit is not a pest in the garden. The Mediterranean fruit fly (Ceratitis capitata) is a small fly, 3-5 mm, native to Africa. In Australia it is confined to Western Australia. It has a yellow body and legs, and a brown upper body with a pale yellow pattern. The wings have yellow and brown colouring on them.

Adult size: 6-8 mm

Out and about

They like the warmer, humid conditions and are most abundant from mid spring to early autumn when plants are producing fruit. Their numbers decrease over winter and adults will shelter and survive, but if the weather remains warm and there is still fruit happening, they will continue to be around. They are active in the early morning and late evening. There are over 4,000 species worldwide with about 350 native to Australia but most of them do not do any damage to commercial crops. At the moment Australia doesn’t have the many species that are serious pests in other countries.

Reproduction and Life cycle

The tiny (1 mm) eggs are white and crescent-shaped, hatching into pale cream maggots (6-8 mm). The maggots become more yellow as they develop, finally emerging and dropping onto the ground where they pupate in the soil. In ideal conditions the life cycle of one generation can be completed in 4 weeks. The female can lay hundreds of eggs in her lifetime and they live for many weeks, feeding on honeydew and nectar.

To deter

To control

- Spinosad is a naturally occurring bacterium which disrupts their nervous system causing a quick death. There is a product available that contains spinosad with fruit fly pheromones added to it so that it attracts and targets only fruit flies. This has been devised for the Queensland fruit fly but we don’t seem to get the cucumber fly either when this is applied. Apply to something near the plant (such as stakes) at intervals of a few metres. It is not necessary to apply it on the plant or the fruit for it to work. - Commercial traps are available which lure the male fruit fly. They can be used as an indicator of the presence of fruit flies - Cover fruit to prevent fruit flies from laying eggs - Clean up ALL rotted and rotting fruit and place in a black plastic bag or in the freezer for a few days to kill them. DO NOT ADD TO COMPOST.

Plants to repel

Basil (plant with tomatoes) / Lad’s love and other plants that repel flies may help

Plants to attract

Predators

Why they are a Pest

The female fly lays her eggs in a wide range of fruits. The eggs hatch into maggots that feed on the fruit as they develop, causing it to rot from the inside. Evidence of fruit having been stung is visible as small brown marks that may be raised lumps. In places where the cucumber fly has stung the fruit there is browning off around the area within the fruit. The cucumber fruit fly seems to have a more limited range of fruits it attacks, mainly cucurbits (cucumber, pumpkin, marrows, zucchini) as well as tomatoes, papaw, guava, and passion fruit.