Queensland Fruit Fly
Bactrocera tryoni
Australia's most damaging horticultural pest. Attacks a huge range of fruiting vegetables and tree fruits across the eastern seaboard.
Background
The Queensland fruit fly (QFF) is native to eastern Australia and is responsible for major fruit and vegetable losses across Queensland, New South Wales, and increasingly Victoria and South Australia. Females pierce ripening fruit with a needle-like ovipositor and lay eggs beneath the skin. The larvae then tunnel through the flesh, causing premature fruit drop and rot. QFF has multiple overlapping generations per year in warm climates, which is why trapping and hygiene must be continuous once adults are active.
Fruit fly is a notifiable concern in fruit-fly free zones, and home gardeners in Greater Sydney, the Riverina, Victoria and SA all play a role in suppressing outbreaks.
How to identify
- Adult: ~7mm long, reddish-brown body with distinctive yellow shoulders and markings on the thorax
- Clear wings held flat when at rest
- Larvae: 8-10mm creamy-white legless maggots inside fruit
- Damage: small puncture mark (sting) on fruit surface; internal tunnelling; fruit ripens unevenly and drops early
Life cycle
Female lays 1-10 eggs per sting, multiple stings per fruit. Eggs hatch in 2-4 days. Larvae feed for 7-10 days, then drop to soil and pupate. Adults emerge 10-14 days later in warm weather. Lifecycle as short as 3-4 weeks in summer, extending to several months in cool conditions.
Weather triggers
- Temperature: 15-35°C
- Adult activity peaks between 20-30C. Below 10C adults become largely inactive; pupae can overwinter in soil.
Peak season (southern hemisphere)
Red = active season · Dark red outlined = this month
Affected vegetables & crops
Click any crop to see current prices and growing info.
Climate zones at risk
Organic & low-impact control
- Exclusion netting or fruit bags (1.6mm mesh or smaller) before fruit ripens
- Protein-based lure traps (Cera Trap, Eco-Naturalure) hung from early spring
- Spinosad-based bait sprays applied to foliage weekly when adults are active
- Strict fruit hygiene — collect every fallen fruit, seal in black plastic, solarise for at least a week before disposal
Chemical control
- Dimethoate and fenthion once used as cover sprays are now tightly restricted and generally not available to home gardeners
- For home gardens, organic spinosad-based options are the practical choice
Always read product labels — registrations change.
Prevention
- Cover developing fruit with exclusion bags the moment fruit sets
- Pick fruit slightly under-ripe and finish ripening indoors
- Keep male lure traps active from August through autumn
- Follow interstate fruit movement restrictions — do not transport home-grown fruit across biosecurity borders
Companion planting
No companion plant reliably repels Queensland fruit fly. Basil, marigold and nasturtium have folklore associations but are not a substitute for netting and traps.
Biosecurity
Suspicious fruit fly activity in fruit-fly free zones must be reported to the relevant state authority (NSW DPI, Agriculture Victoria, PIRSA). Interstate movement of host fruit is restricted.
Sources
- Queensland DAF — Queensland fruit fly: https://www.business.qld.gov.au/industries/farms-fishing-forestry/agriculture/biosecurity/plants/insects/fruit-flies/queensland
- NSW DPI — Queensland fruit fly: https://www.dpi.nsw.gov.au/agriculture/horticulture/pests-diseases-hort/queensland-fruit-fly
- Agriculture Victoria — Queensland fruit fly: https://agriculture.vic.gov.au/biosecurity/pest-insects-and-mites/priority-pest-insects-and-mites/queensland-fruit-fly
Accuracy confidence: high. We update this library as new extension guidance is published.