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A good time to discuss this persistent pest again as our fruit trees flower and prepare to fruit.

Found a very helpful website dedicated to giving advice to home gardeners FRUIT FLY AND THE HOME GARDENER.

First thing - Fruit Fly and the tiny annoying Vinegar Fly that comes into your house looking for rotting fruit, are two different beasties.  FF lay eggs on your ripening fruit on the tree (see life cycle below) and looks like this: Queensland Fruit Fly Bactrocera tryoni

I've recently gone through a bottle of Wild May and while it did kill many FF it was expensive and I now have to source more.

Perhaps there are some simpler ways we can use to protect our fruit. Many are having success with exclusion bags. Not an option for me on a large Carambola with dozens of fruit though.

I thought I might share my search this morning for alternatives.

Remember to dispose of any fallen fruit thoroughly. Do not compost! I throw mine into the weed tea container to drown and return their nutrients back to the garden.

Understanding our foe can be a big help.

LIFE CYCLE

There are four stages to the life cycle of fruit flies, these are: eggs, larvae (maggots), pupae and adults. A brief description of each of the stages of the life cycle of fruit fly is provided below. Note that the life cycle of most fruit flies (Tephritidae) species is similar. 

Eggs

The female adult fly lays eggs (1-20)  into the maturing and ripening fruit of the host plant. The eggs hatch into larvae inside the fruit after a few days (2-4 days). Note that at this stage of the lifecycle you are unlikely to be able to recognise the presence of fruit fly eggs in your fruit. 

Larvae

The hatching larvae (maggots) feed on the flesh of the fruit, gradually moving towards the centre of it. The feeding activity of the larvae causes the fruit to prematurely ripen and rot. The larval stage is the most likely stage that you would recognise the presence of fruit fly in your fruit if you cut it open. 

Pupae

As the fruit ripens and rots, it falls to the ground. Fully mature larvae leave the fruit and burrow into the soil to pupate. In the soil, larvae become inactive and change into oval, light to dark brown, hard pupae, in which adult flies develop. At this stage you are unlikely to recognise the presence of fruit fly pupae in the ground. 

Adult

The adult flies may emerge from the pupae in as little as seven days during the summer, or after several months over winter. The adult fly looks for the nourishment it needs to reach maturity, breed, and lay eggs in new season crops. At this stage of the lifecycle you may be able to recognise adult  flies landing on or hovering around fruit. 

Life cycle of fruit fly

Life cycle of fruit fly

Behaviour of fruit fly

Fruit fly numbers tend to increase, usually in spring, when temperatures are warm and there is continued availability of suitable host plants. Fruit flies develop from eggs to adults within four to five weeks. 

Adult flies (both male and females flies) usually: 

  • are most active from October to May (some activity will occur in warmer periods during the winter months)
  • are most active from dawn to the first few hours of the day
  • rest in shady trees (fruit trees, ornamental trees and shrubs) during the day
  • feed in the host tree
  • mate at dusk
  • are strong fliers and can travel some distance
  • can survive throughout winter

Female fruit flies usually: 

  • lay eggs into healthy, maturing and ripening fruit (on the tree) and vegetables
  • need to feed on a source of protein before eggs will mature for laying
  • only mate once in lifetime
  • must wait about five days before commencing egg laying
  • reabsorb egg during extended periods of cold weather

TRAPS

Green Harvest sell something called Cera Traps and Econaturelure. Again, both very expensive. Does anyone have experience using these particular products?

I would like to try Cera but a 5lt bottle costs $100 (I'd make my own traps) but the blurb in the ad says the traps become active when opened and exposed to oxygen - hopefully the 5lt bottle comes with a way of dispensing small quantities without this happening.

Lots of simple FF traps (wondering whether they mean Vinegar Fly traps) on the net so, for the sake of economy, I've made a couple from plastic bottles with fruit juice added sugar and a titch of detergent. Hopefully I won't live to regret my cheapness by losing my entire crop of Carambola.

Here's a good little article from GARDENING AUSTRALIA:

Fact Sheet: Fruit Fly

Josh Byrne discusses methods of dealing with this annoying pest

Presenter: Josh Byrne, 23/10/2010

SERIES 21 Episode 35

There are over two hundred species of fruit fly in Australia. The good news is that only two of them - the Queensland fly on the east coast and the Mediterranean fly on the west coast are problems for gardeners.

Both species have similar host plants, including citrus, loquats, stone fruits, apples, pears, avocados, bananas, mangoes, guavas, feijoas, tomatoes, eggplants and capsicum.

Fruit fly trouble begins as the weather warms in August. Flies lay their eggs under the skin of ripening fruit, maggots hatch and feed, spoiling the fruit, causing it to rot and drop.

The first and most important step when attempting to prevent fruit fly attack is good hygiene. Mature maggots pupate in the soil to remerge as adult flies and collecting infested fruit breaks their lifecycle. Signs that eggs have been laid in fruit are dimples or weeping clear sap on the fruit. Pick these fruit off as well as any damaged and rotting fruit. It's also important to pick up fallen fruit as soon as it drops before maggots have a chance to escape from the fruit and burrow into the ground to pupate.

To kill maggots, immerse them in a sealed bucket of water for a couple of days (I throw infected fruit into my Weed Tea bucket to drown and return their nutrients back for garden use) or put them in a sealed plastic bag and put it in the sun. If you have chooks, they will appreciate them!

Trapping adult flies helps limit the breeding population. There are numerous variations of traps and lures but Josh's version is very easy.

Josh says, "Start by making some holes half-way up a plastic drink bottle. They should be about 10 millimetres wide and evenly spaced." Josh recommends fruit juice for the lure but he also adds a pinch of sugar and a sprinkle of brewers' yeast to make fermenting sweet syrup that, Josh says, "Fruit flies just can't resist."

Hang two or three traps per tree and change the lure weekly when the pests are active. There are also commercial pheromone traps and effective, certified organic bates available from garden centres.

Please note that this mixture may also attract other insects.

Use 'exclusion' bags to keep fruit safe. There are numerous sized bags available depending on the type of fruit you want to protect, and most are re-usable. The bags also keep birds out as well as protect the fruit from sunburn.

Josh says, "We all need to be vigilant to keep fruit fly under control because neglected trees become a neighbourhood problem. Please do your bit and then we can all enjoy the fruits of our labour."

Watch the story

Article from SURF COAST NEWS on Qld FF:

If you have fruit trees in your yard you should:

  • Prune them regularly, keeping the tops of the trees at a manageable height.
  • Regularly inspect your home-grown fruit for the presence of maggots.
  • Remove any ripe fruit from your trees before it falls to the ground.
  • Don’t take any fruit from your property without processing it (eg by cooking) first.

If you suspect there is QFF in your fruit you should:

  • Collect and dispose of fallen fruit on an ongoing basis. Fruit infested with QFF can be disposed of in a sealed plastic bag, which is either left in the sun for 5 to 7 days or placed in a freezer for two days. This will destroy the maggots and prevent adult flies from developing. The bagged fruit can then be discarded in your garbage bin.
  • Compost carefully – do not place unwanted fruit in your compost or worm farm, or put it directly into your garbage.
  • Remove any unwanted fruit trees from your property.

source: The Department of Primary Industries Media Release

Links

  • Visit the DPI website at www.dpi.vic.gov.au/qff for more information on protecting your fruit trees from a QFF infestation, alternatively you can call the QFF Hotline on 1300 135 559.
  • The national website www.preventfruitfly.com.au also has more detailed information on controlling QFF in the home garden as well as a list of suppliers and resources.


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Replies to This Discussion

That's very helpful Kathy, thank you. In case anyone wants to check them out and buy some.

I've noticed that fruit of the black krim isn't molested by fruit flies whereas the normal red ones I have growing alongside are regularly stung if I don't bag them while they're still very green.

That's interesting. You would think the smell of tom would attract them, maybe colour has something to do with it.

I think it's the scent as the tomatoes are stung while they're still unripe. The black krim plant smells different to other tomatoes.

mosquito nets and lace curtains are the best thing for the fruit - but they are getting rarer and more expensive.  you used to be able to pick up lace curtains and old mozzie nets just about anywhere  - but the news is out and everyone wants them

I have heard this before but didn't take action. I've just had a look on eBay and was quite surprised at the cheap cost and even free delivery. I've bought one in the hope that someone can help me get it over my Carombola before the fruit gets any more mature. Thanks Tony :)

hello fellow gardeners, well after last season my tomato's getting hammered by these little bugs, I have bought the bags from green harvest (thanks rob bob) and while they aren't the easiest thing to fit it will be worth it to have clean unspoilt fruit.

Good that you had success with them Brad :)

I tried them out once and found it a little frustrating having to open them to check the fruit, plus I must have put them on too late as the fruit was still stung.

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