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Pests of plants: Exotic fruit flies
Profile There are more than 150 species of fruit fly already in Australia, but most of these don’t attack commercial crops. It’s the exotic fruit flies present in many of our neighbouring countries that pose high risks to our agricultural industries, and that could devastate many of the crops we rely on for our food and economic well-being.
Identification Female flies pierce the fruit’s skin to lay their eggs beneath the surface, along with bacteria that start fruit rotting. The eggs develop into maggots, which drink the rotting pulp. Flies can grow from eggs to adults in about four to five weeks. The adults are about 7mm long and often yellowish. Eggs are about 1-2mm long and whitish. The maggots are creamy-white and about 12-20mm long.
Photos below: Images of Papaya fruit flies and a fruit fly trap
Distribution In New Guinea and Indonesia there are several fruit flies that we must keep out of Australia, including melon fly, papaya fruit fly and its close relative Filipino fruit fly.
Threat In 1995, papaya fruit fly devastated fruit crops around Cairns and cost $33.5 million to eradicate. If another outbreak occurred in northern Australia, restrictions would be placed on fruit that could be sold to other States and Territories, or overseas. Apart from the eradication costs, there would be severe restrictions on the movement of produce as well as commercial losses including jobs and income.
Keep a Top Watch The most likely way for exotic fruit flies to enter Australia is in infested fruit. All commercial imports of fruit and vegetables are disinsected or are certified as being grown in a fruit fly free country or region. Non-commercial imports, such as fruit and vegetables entering Australia with travellers, are destroyed. NAQS maintains a system of fruit fly traps across northern Australia. These traps have been set up to check if any new species are entering the country. Don’t move or break them. If you see a broken trap, contact Quarantine so it can be replaced. Never trade fruit or vegetables from New Guinea and make it a rule not to carry produce south to other parts of Australia.