Queensland Fruit Fly (Bactrocera tryoni), which is now making its pesky presence felt in the suburbs of Melbourne; 
WHAT: Queensland Fruit Fly (QFF) is native to coastal north-eastern Australia but has now spread inland to the NT and south to Victoria. It’s tiny - adults are only 7mm long - but it leaves tell-tale signs on fruit: dimpled skin and maggots infesting the fruits.
WHERE: The flies have spread because humans are providing them with host plants, which include: Pome fruits, stone fruits, figs, grapes, citrus, tomatoes, capsicums, flowering plums, ornamental pears, lily pillies and even clivia.
Ranger Stephanie Orive, Land Management Officer with the Shire of Nillumbik, explains that Victoria’s winters rarely get cold enough to kill off fruit flies, especially in urban areas. Residential gardens may just be the perfect place for female QFFs to overwinter “under eaves, in leaves and tree fissures”.
WHEN: As the weather warms in spring, the adults emerge and breed. As the eggs hatch, the maggots then feed upon the fruit flesh.
WHY: While QFF may be a pain for backyard fruit and vegie growers, it can be devastating for farmers, and mean more expensive fruit and vegetables for shoppers, so there are a lot of good reasons to try and control it.
  1. Monitor and report: make a homemade QFF Trap (see below) and report any sightings to local or state authorities.
  2. Prune trees to a reachable height so you can harvest more easily.
  3. Exclude with netting, bags or sleeves to stop the female QFF from reaching and laying eggs inside fruit and vegetables. Use specific fruit fly netting, fine gauze or mosquito net - or even old lace curtains; the key to success is openings of just 1.6mm. Ensure the mesh is not touching the fruit. 
  4. Garden hygiene – collect all dropped fruit, and dispose of all unwanted fruit.
  5. Infested fruit should never be composted – instead bag it and either freeze or microwave to kill larvae
  6. Collaborate with community – Get to know your neighbours, and encourage whole community involvement and action to manage this pest.
To make a fruit fly trap
What you’ll need:
  • 1L to 2L clear plastic bottle with a lid
  • Yeast extract
  • Sugar
  • Fruit peel
  • Water
  • Knife
  • String
What you do:
  1. Put a spoon full of vegemite and a spoon full of sugar in the bottle, plus the peelings from an orange or lemon.
  2. Add enough water to fill the bottle to about a third, put on the lid, and shake until the yeast extract and sugar have dissolved.
  3. Using the knife, carefully cut an access hole further up the plastic bottle.
  4. The trap can be hung with the string near a fruit tree.