Queensland fruit fly

Page last updated: Wednesday, 5 September 2018 - 11:35am

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Queensland fruit fly (Qfly, Bactrocera tryoni) is native to Australia. It is considered to be one of the most serious pests of fruit and vegetables and attacks a larger range of crops than Mediterranean fruit fly (medfly), which is present in Western Australia.

Qfly is found in New South Wales, the Northern Territory, Queensland and Victoria.

Western Australia, South Australia and Tasmania are free of Qfly. Outbreaks of Qfly are most likely to occur from November to May, but some activity may continue during cooler months of the year.

Symptoms of damage

Queensland and Mediterranean fruit flies feed internally on fruit. The female fly lays its eggs into fruit and vegetables, and may cause some damage around the puncture mark (sting). This is followed by decomposition of the fruit.

Examples of fruits attacked by Qfly but not Medfly include avocado and capsicum.

Identifying Queensland fruit fly

Queensland fruit fly
Adult Queensland fruit fly (Bactrocera tryoni)

Adult Qfly are approximately 6-8 mm long, have three body segments, wings and 6 legs. The head has two red eyes with two very short antennae (only visible under close inspection). The thorax (middle segment) is reddish-brown with yellow patches on the sides and back. The abdomen (end segment) is a solid dark brown, the legs are a lighter shade of brown and the wings are clear.

Don't confuse Qfly for Mediterranean fruit fly (Medfly), which is smaller (approximately 3-5mm long). The head of Medfly also have red eyes and two very short antennae. Its thorax (middle segment) has irregular patches of black and silver, giving it a mosaic appearance and the abdomen (end segment) is orange-brown in colour and encircled by two lighter coloured rings which can look silvery in the sun. Medfly wings are transparent and mottled, with distinct pale brown bands extending to the wing tips. Refer to the Medfly web pages for more identifying information.

The eggs and larvae of Qfly and Medfly look identical and cannot be easily distinguished from one another. Samples or photos of adult flies caught in fruit fly traps or photographed on the fruit can be submitted for identification and screening (see reporting details below). The presence of thin, white larvae in green tomatoes, unripe fruit, chillies and passionfruit is worth reporting so we can screen for Qfly as Medfly larvae are not often found in these hosts.

Life cycle

All fruit flies have a similar life cycle. The adult emerges from a pupa in the soil. The pupal case is dark brown.

Once mature, the adults mate and the female lays eggs just under the surface of the fruit. The eggs are white and about 1-2mm long. The maggots or larvae hatch from the egg and start feeding on the fruit.

This makes the fruit unsuitable for human consumption, and introduces bacteria and the fruit starts to rot. However, the fruit can appear to be sound. Larvae quickly grow from 1mm to 1cm long when fully grown. The fully grown larva jumps from the fruit and drops to the ground, tunnels into the soil and changes into a barrel-shaped pupa.

The life cycle is more rapid when temperatures are high. In summer, both species can develop from egg to adult in three weeks. Adult flies can live for months.

Report any suspect sightings

If you suspect you have seen Queensland fruit fly, please take photos where ever possible and:

Make an online report (mypestguide.agric.wa.gov.au) or use the MyPestGuide reporter app (mypestguide.agric.wa.gov.au)

Phone: (08) 9368 3080   or

Email: padis@dpird.wa.gov.au 

Contact information

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080