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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

Yes, it's a good article. However … I suggest a simpler alternative. *Feed the soil* Working on the theory that a really healthy plant will not attract much in the way of pests and diseases. I have made this point before and won't bore readers with a repetition. I do get the odd fruit stung. And my observation is that always the plants are struggling. Whether from nutrient deficiency, lack of water, unseasonal weather, out of season for that plant or an inappropriate spot for that plant. It is a more long-term and complex solution but in the end, you don't have to buy anything extra and there's no poisons involved. Remember that 'natural' poisons like Pyrethrum will kill any insect which contacts it. Whether friend or foe.

Great advice Elaine! Couldn't agree with you more!

When we have fruit flies inside  we make this simple cheap trap: Fill a bowl with a couple of Tbsp of either apple cider vinegar or any leftover wine (especially sweet wine. Port works really well but more expensive) cover with glad wrap and pierce a few holes (skewer or tip of knife size). Flies can enter but no fly up. You can also use apple cider vinegar and a drop of dishwasher liquid without the glad wrap because the dishwasher liquid kills them. I find the first method more effective and I feel safer putting that in my compost.

That's the vinegar fly you get inside the house Val. Little sods come right through the screens. Elaine has given a good description of the three different fly below.

What about garden lime on the ground? Doesn't that deter fruit flies? That's the advice with worm farm and compost, isn't it?

Fruit flies and vinegar flies are two different animals. Fruit flies sting (lay eggs in) ripening fruit. Vinegar flies are the tiny critters you can see flying around rotting fruit and they would be the ones attracted to the trap you described. Normally neither would bother a worm farm. The pest of worm farms is the Soldier fly - a big black thing which lays eggs on rotting vegetation which is acidic hence the lime.

Bought some Yates Fruit Fly Control to try this time. $26 for 200ml at Bunnings - dilutes in spray bottle for spot application weekly to tree trunk.

Contains spinosad "an insecticide derived from naturally occurring beneficial soil bacteria which kills fruit fly".

Woo hoo, Lissa - look up that stuff. It's a systemic and will kill anything which contacts it. There should be some posts from Scarlett about it on this forum, going back 3-4 years.

I do vaguely remember conversations about it before. Will look it up before I use it. Thanks Elaine.

Fruit Flies - aaarrrggg. I declared all-out war against them at the start of summer, but have found so far the only thing that works 100% for protecting my tomatoes is exclusion bags. I have tried Wild May, Cera Trap, Eco-Naturalure and Neem Oil.

Wild May catches lots of fruit flies. When I first put it out I caught 15 fruit flies in one trap in the first 20 minutes. I had about 5 traps out around my tomatoes, the traps were filling up with flies almost faster than I could top them up with Wild May, but I was still getting stings on my green tomatoes I tried a Ceratrap at the same time, but only caught a handful of flies. I read somewhere that the females do not like entering through small holes so I made the holes on my home-made Wild May traps large. The Ceratrap had smallish round holes. In addition to these two traps, I also painted Eco-Naturalure inside milk cartons and on some wooden stakes. I have no idea if this worked as it does not trap the flies, but is supposed to attract the female fruit flies, which eat the spinosad laced bait, and I guess die somewhere else - it is supposed to only attract fruit flies.

But I ended up deciding that because I was living in a suburban area I was not going to significantly reduce local fruit fly numbers as there are so many nearby sources. I know a tomato farmer who lives in a more isolated area north of Brisbane, who uses Wild May and nothing else. Wild May attracts the male and juvenile females and so if you are fairly isolated with no nearby neighbours with fruit, you could reduce your local population of fruit fly.

I have also read that Neem Oil deters fruit flies from laying eggs in fruit - oviposition deterrent. This was overseas resarch with different fruit fly species and I am not sure how effective it really was. I sprayed once one evening, but I cannot say if it had any impact. Neem oil is supposed to also have anti-fungal properties.

I have tried three types of exclusion bags for my tomatoes. Green Harvest has lovely soft-material type bags they designed for tomatoes that are easy to tie on, plenty large enough for tomato trusses and you can see the fruit ripening. However, I am finding that they seem to deteriorate out in the elements and will possibly not be able to be used multiple times - Green Harvest does not claim that they last longer than one season, but I was hoping that they might. I have also used waxed paper bags designed for fruit (also bought from Green Harvest) - you cannot see the fruit ripening, but they survive storms and downpours well. But you cannot wash them and they are a bit fiddly for tomatoes. My favourite bags are ones I bought from a gentleman in Sunnybank Hills that are made from UV stabilised poly-plastic and breathable material - they are strong and survive the washing machine well.

Thanks Kathy! Good info.

Do you have contact details you can post here for the gent in Sunnybank Hills?

I do not know his name, but while searching for fruit fly exclusion bags I found him on ebay. I sent him an email message via Ebay and organised to pick up some bags as he lives in the next suburb to me. He has medium size bags that I use and then extra large bags. This is his ebay page: http://www.ebay.com.au/usr/fruit_orchard

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