Queensland Fruit Fly

If you have fruit trees or vegetables in your garden, you need to look out for and control Queensland fruit fly (Qfly) – an established pest found in eastern Australia that poses a threat to horticultural crops and home gardens if not properly managed.

Example host fruits for Qfly include stone fruit, citrus, apples, tomatoes, capsicums, chillies, feijoas, loquats, guavas, figs, cherries and berries, leaving them inedible.

Sting marks on the fruit are often the first sign of a Qfly infestation, and sometimes fruit will soften, discolour or rot. Inspect fruit regularly for signs of Qfly:

• Start checking when fruit has reached its full size but before colour change. Qfly can lay eggs in fruit that is still hard and green.
• Look for small spots (sting marks) on fruit surface or sap seeping from fruit.
• Cut fruit open and look for larvae. They are very small (1–2mm) when they hatch, so you might need a magnifying glass.
• If you find infested fruit, remove and destroy it as soon as possible.

Accurately identifying any pest is crucial for effective control. Qfly is very small but can easily be identified once you know what you are looking for. For example:

• Adult flies: 5–8mm long, reddish-brown in colour with distinct yellow markings.
• Females: have an ovipositor (commonly referred to as a “stinger”) used to lay eggs into fruit.
• Qfly maggots: initially 1-2mm in length but will grow up to 8mm long, creamy-white in colour, often found in the centre of fruit. 

Controlling Fruit Fly

Remove unwanted fruit trees: Remove unwanted or unmanageable fruit trees (treating any remaining stump to prevent regrowth) and consider replacing them with a non-fruiting tree.

Plan your garden: Consider planting fruits and vegetables that are not hosts for Qfly. For fruit and vegetable plants that are prone to Qfly infestation, design the layout of your garden so an insect-proof net can be used to protect these plants.

Hang traps and lures: Traps are used to identify when Qfly are present and may help to reduce numbers, but they are not an eradication solution. 

• Use traps and lures (purchased or DIY) to detect Qfly activity in your garden.
• Replace or refill traps regularly.
• Use traps in conjunction with other control methods.

Use insect-proof netting: The most effective way to stop Qfly from damaging your fruit and vegetables is to cover them with insect-proof nets (purchased from gardening centres, hardware stores or online). Nets should have net/mesh holes no bigger than 3mm. 

• In winter, trees should be pruned to about 2m to help the net fit over the tree and prevent damage to the net.
• Cover trees after flowering and pollination, as soon as fruit forms.
• Remove the net after harvest, clean it, and store away for next year.

Practise good garden hygiene: Check your fruit regularly for signs of Qfly, reduce tree heights to make it easier to pick fruit, thin trees to manage crop yields, pick fruit early, remove any fallen and leftover fruit and dispose of it immediately and correctly.

Safely dispose of infested fruit: Do not place infested fruit in the green bin or a compost area. Disposal options include:

• Place all infested fruit (including fruit on the ground) in double garbage bags and leave in full sun for 10–14 days to destroy eggs and maggots.
• Boil or microwave infested fruit, cool and place in garbage bags.
• Seal fruit inside a plastic bag and freeze for two days.
• Dispose of bags of treated fruit in the general waste bin.

For more information, visit your local nursery or home garden store and refer to the list of resources below.

For Travellers

If you are travelling within Australia, find out what restrictions might apply where you are going. For example, eat or dispose of fruit and vegetables before entering South Australia.

For up-to-date information, refer to:

[National] https://interstatequarantine.org.au/ or free call 1800 084 881 during business hours.

[South Aust] https://fruitfly.sa.gov.au/travelling-restrictions or free call 1300 666 010 24 hours a day.

Remember to look for road signs advising on restrictions and place all restricted items into bins provide.

Support local growers, buy local, don’t travel with or share infested fruit.

Resources

https://agriculture.vic.gov.au/biosecurity/pest-insects-and-mites/priority-pest-insects-and-mites/queensland-fruit-fly/controlling-queensland-fruit-fly-in-home-gardens  

https://agriculture.vic.gov.au/biosecurity/pest-insects-and-mites/priority-pest-insects-and-mites/queensland-fruit-fly/queensland-fruit-fly-host-fruits  

https://agriculture.vic.gov.au/biosecurity/pest-insects-and-mites/priority-pest-insects-and-mites/queensland-fruit-fly/controlling-queensland-fruit-fly-languages-other-than-english  

[Brochure] https://agriculture.vic.gov.au/__data/assets/pdf_file/0005/532139/Managing-Queensland-fruit-fly-in-your-home-garden.pdf