New Guinea fruit fly

Adults

• About the same length (approximately 7mm) as a common housefly but more slender like a small wasp.
• Clear wings.
• Mainly black body.

Eggs

• White to yellowish-white, long elliptical – like a sickle, and approximately 1-2mm long.

Larvae

• Maggots are creamy-white and up to about 10mm long at full size (younger stages are smaller).

Pupae

• Varies in colour from white to yellow-brown.
• Roughly cylindrical and about 5mm long.
• Typically found in the soil.

Plant stage and plant parts affected

• Ripening fruit are affected.

Plant damage

As with other fruit fly species, females 'sting' the fruit when they lay their eggs inside. Larvae hatch from eggs and tunnel into the fruit, and considerable damage can occur inside the fruit before obvious signs can be seen on the outside of the fruit.

Fruit decaying bacteria are also deposited within the fruit during the egg laying process. These bacteria also contribute to fruit damage.

The most obvious signs of infestation are:

• small discoloured or water-soaked patches on the fruit skin, which develop from the stings
• affected fruit rotting and often falling from the plant prematurely.

The Queensland fruit fly is a similar size and colour to New Guinea fruit fly, but is red-brown instead of black. An expert is needed to identify New Guinea fruit fly under a microscope. Male lure traps used to catch Queensland fruit fly can also catch New Guinea fruit fly.

Widespread on the island of New Guinea including Papua New Guinea and Indonesian West Papua.

New Guinea fruit fly is known to infest 17 host plant species in 10 families including commercial hosts such as mango, peach, carambola,citrus, guava, chilli and lilly pilly.

• Adult female flies lay their eggs just under the skin of fruit and also deposit fruit decaying bacteria.
• Within 1–2 days, eggs hatch into larvae (maggots) that feed on the decaying fruit, causing premature fruit drop.
• Depending on a range of factors, including temperature, after 6–35 days the larvae drop from the fruit to ground level, bury in the soil, and pupate.
• Flies emerge after another 10–12 days (depending on conditions), becoming sexually mature after 1–2 weeks.
• Flies live for several months; females are capable of laying eggs throughout their life span once mated.

In 2020–21, the gross value of production of Queensland horticulture crops (excluding cut flowers, nursery and turf) was $2.9 billion (Queensland AgTrends).

Costly quarantine restrictions and eradication measures will be needed if New Guinea fruit fly were to arrive and establish in Australia. It would have serious consequences for our horticultural industries as many countries have trade restrictions on produce from regions known to have New Guinea fruit fly. Growers would likely face difficulties exporting their produce.

Home growers with backyard host plants would also be affected.

New Guinea fruit fly could easily be brought into Australia by illegal importation of infested fruit.

New Guinea fruit fly occasionally moves into the Torres Strait with monsoonal winds in the wet season and is eradicated as part of a highly successful, proactive eradication strategy.

Like most tropical fruit fly species, New Guinea fruit fly multiplies rapidly and can spread over large distances.

If you have fruit and vegetables that have had no problems with fruit fly in the past but are now infested with maggots, then it is possible that you have an exotic fruit fly species on your property.

Keep a look out and contact Biosecurity Queensland on 13 25 23 if you notice unusual fruit flies or there are changes in the pattern of fruit fly damage to your crops.

• Protect your farm from emergency plant pests
• Understand good farm biosecurity
• Visit the farm biosecurity website

The nationally cost-shared Exotic Fruit Flies in Torres Strait Eradication Program undertakes surveillance for New Guinea fruit fly and other exotic fruit fly species that may be seasonally dispersed from Papua New Guinea to the Torres Strait Islands with the summer monsoon season. Any incursions are eradicated immediately.

The program includes:

• trapping and identifying fruit flies for early detection
• using pheromone-based insecticide baits (blocks) to attract and kill male fruit flies
• using protein-based insecticide bait (spray) to kill adult female flies
• movement restrictions to prevent pest introduction and spread by movement of infested fruit and vegetables.

New Guinea fruit fly is prohibited matter under the Biosecurity Act 2014.

Report suspected New Guinea fruit fly to Biosecurity Queensland immediately on 13 25 23 or contact the Exotic Plant Pest Hotline on 1800 084 881.

If you think you have found New Guinea fruit fly, you must take all reasonable and practical steps under your control to minimise any associated risks. This is called a general biosecurity obligation (GBO).

New Guinea fruit fly is also a declared far northern pest in Schedule 8 of the Biosecurity Regulation 2016. The far northern biosecurity zones (PDF, 333KB) have been established to prevent the spread of far northern pests.

Regulations are in place to restrict the movement of fruit and vegetables, plants and other plant material, soil and equipment (collectively called far northern pest carriers) which may harbour pests and diseases. You must apply for a biosecurity instrument permit to move any of these items out of the far northern biosecurity zones.

It is illegal to move a far northern pest such as New Guinea fruit fly or far northern pest carriers without a biosecurity instrument permit:

• from far northern biosecurity zone 1 to a place outside of that zone
• from far northern biosecurity zone 2 to a place outside that zone unless it is into far northern biosecurity zone 1.

You must observe movement restrictions if you are travelling to or around the Cape York Peninsula, or you live there.

For more information about biosecurity instrument permits, contact the Customer Service Centre on 13 25 23 or email qld.plantquarantine@daf.qld.gov.au.

Your cooperation in complying with these restrictions will help protect Queensland from exotic fruit fly outbreaks.