10 things you didn’t know about fruit flies

Robin Powell reports from behind enemy lines on the fascinating, infuriating fruit fly.

Words by Robin Powell

Fruit fly. Photo -

1. There are close to 5000 species of fruit fly in the world, with 270 native to Australia, 10 of which attack commercial varieties of fruit. The Queensland fruit fly is the major curse of gardeners on the east coast.

2. The little fly buzzing around the fruit bowl when fruit is overripe are vinegar flies. These are much smaller than Queensland fruit flies.

3. It takes temperatures of -5 degrees three days in a row to kill an adult fruit fly! They survive the winter chill by hanging out in the canopies of evergreen trees, especially those close to houses or compost heaps that might generate a bit more warmth. They become active once temperatures get to around 15 degrees.

4. The female’s ovipositor both pierces a hole in the skin of the fruit, and positions the eggs in the fruit. The ovipositor of the Queensland fruit fly is strong enough to pierce the skins of even tough fruit like passionfruit, pomegranate, walnuts and almonds.

5. The resistance of cherry tomatoes to fruit fly attack is thought to be because the skin is too shiny and slippery for the female to get a good grip and sting the fruit.

6. Lychees and finger limes repel fruit fly attack because the juice under the skin is under so much pressure that the fruit fly sting causes juice to explode out of the tiny hole, taking the newly laid eggs with it.

7. The female spits on the fruit before she stings it and positions her body to sting through the saliva, taking bacteria into the hole, which immediately starts to break down the cells of the fruit, offering an instant food source to the hatching eggs. That’s why the skin around a sting feels soft to the touch.

8. Eggs hatch 24-48 hours after they are laid, and the larvae grow in the fruit for between 7-40 days before jumping out of it.

9. The pupae stay in the ground, or in mummified fruit, for a minimum of 10 days and up to about 20 days in cool weather. They are a popular food source for chickens.

10. It takes just one to two weeks for a fly to develop from an egg to sexual maturity, mate and lay more eggs. Adult fruit flies can live for about four months.

Eliminate fruit fly:

1.Be clean.

In winter make sure all fruit is off trees, and there is no fruit fallen on the ground that would provide safe habitat for fruit fly larvae. This includes lillypilly fruit which are recorded hosts for fruit fly. Don’t put fallen fruit straight into the compost bin. Boil it first.

2. Monitor

Keep an eye out for fruit fly activity. Hang traps in target trees from spring through autumn, and in evergreen trees in winter to kill fruit fly and indicate population changes. Check fruit for signs of stings.

3. Deal with the threat

When fruit flies are identified in traps, start spraying with organic sprays for fruit fly or, use our preferred method for total control, exclusion. Net trees or use exclusion bags over individual fruits, keeping the bag well clear of the skin to prevent attack through the netting.