How to get rid of fruit flies on fruit trees

Expert tips and advice.
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If you grow backyard fruit trees, unfortunately you’ll find there’s a range of pests wanting to get to your harvests before you do. And one of the most insidious is the Queensland fruit fly (which despite its name, is active well beyond Queensland).

Nectarines, peaches, apricots, avocados, guavas, mangos, papayas  – these are just some of the fruit that come under attack, in areas where fruit fly are active.

Nectarine tree
Nectarines can come under attack (Credit: Getty)

The Problem

Fly populations start to build up through spring as temperatures rise, reaching a peak in late summer.

The female flies lay their eggs in small groups, just below the skin of the fruit. When the maggots hatch, they feed on the fruit, causing it to eventually rot and drop to the ground.

What to do

The first step is to find out whether fruit flies are active in your garden, by hanging pheromone-based traps in fruit trees. These attract and kill male fruit flies, so they’re a useful indicator of when you should start a spraying program. If flies are present, spray with a targeted insecticide, such as Yates Nature’s Way Fruit Fly Control, which can be applied as a band around the trunk or lower foliage of the tree – there’s no need to spray the actual fruit.

Avocado tree
Hang pheromone-based traps in avocado trees (Credit: Getty)

Other things you can do

Good garden hygiene is important in reducing fruit fly infestations too. Collect and destroy any rotting fruit, whether it’s on the tree or on the ground, to reduce the risk of the maggots developing and leaving the fruit. Place the produce in a plastic bag, seal it and leave in the sun for 5 – 7 days, or place it in a freezer for two days.

Another useful hint is to grow early-fruiting trees, which can be harvested in late spring and early summer, before fruit fly numbers have built up.

Mango tree
Destroy any rotting mangos (Credit: Getty)

How to make your own fruit fly traps

1) Use a clean soft-drink bottle (with lid).

2) Cut three holes in the bottle (about the size of a 10-cent piece), positioned 10cm from the top.

3) Make up the bait mixture, consisting of 1 cup of fresh fruit juice (including pulp) and one tablespoon of cloudy ammonia, and pour into the bottle.

4) Tie a string around the neck of the bottle, and hang it from the tree in a shady spot, about 1 to 1.5 metres above the ground.

5) The mixture should be changed weekly for best results. (NOTE: These traps may attract beneficial insects also).

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