Oriental Fruit Flies

Fruit flies can become very destructive to fruiting plants, with the oriental fruit fly (Bactrocera dorsalis) being the most prominent. This species is native to tropical Asian countries like Singapore.

The oriental fruit fly has prominent yellow and dark brown to black markings and is sometimes mistaken for a wasp or bee. It however has much larger eyes and can be seen laying eggs in a variety of fruits, particularly cucumber, lime and tomato. It breeds throughout the year, and the females lay about 20 eggs per fruit. While eggs are being deposited in the fruit or soft vegetable parts, fruit decaying bacteria are subsequently deposited as well, which causes affected fruit to start rotting or bruising around the eggs. Larvae will consume the fruit, and once the larvae mature, they exit the fruit and drop onto the ground to pupate, then emerging as adult flies.

Symptoms

Small, discoloured patches on the skin of the fruit will develop after a female fruit fly deposits her eggs. Affected young fruits will become disfigured, callused, and can drop prematurely while affected mature fruits will have a rotten appearance. Tunnels can be seen as the larvae develops and feed.

Preventive and control measures:

Netting, paper, or cloth can be used to wrap the fruits as they mature, creating a barrier to prevent fruit flies from laying eggs. Quickly remove mature fruits from your plant to decrease the chance of them attracting fruit flies to your garden.

As fruit flies are highly mobile, it can be difficult to eradicate them from your garden using sprays. It is best to remove and dispose fruits and plants that have been affected by fruit flies upon discovery to prevent the spread.