Organic Pest Control: Fruit Fly

Fruit Fly - even the mere mention can send shivers up the most experienced gardeners spine. When I first started gardening, I honestly didn’t even know exactly what they were and thought they were flies that enjoyed mangoes - I wish that were true. Not until I harvested my first Tomatoes, cut them open and found little worms wiggling around inside did I realise what a pest they can be. I lost my whole crop to fruit fly that year and it made me realise this was something that I needed to combat in a very effective way if I wanted to grow my own food and actually be able to eat it. If you are in an area that is unaffected by fruit fly then a) you are very blessed and b) this blog may not be for you but for those who are, read on. We will talk about the best strategies I’ve found to deal with them.

First of all - What is Fruit Fly?

There are three types of Fruit Fly that cause headaches for gardeners in Australia - Queensland Fruit Fly, Mediterranean Fruit Fly and Cucumber Fruit Fly. Female Fruit Fly lay their eggs inside the skin of fruit. The eggs then hatch and the Larvae eat the inside of the fruit. This causes the fruit to rot and eventually fall from the tree or vine. Fruit Fly mainly target Fruit Trees, Tomatoes, Eggplants and Capsicum however this year I have noticed them also going for my Squash, in particular my Tromboncinos. 

How do you identify fruit affected by Fruit Fly?

The early signs of fruit affected by Fruit Fly are a small black puncture mark around the size of a pinhead where the fruit has been stung (see photo). Fruit may develop dimpling and start to drip clear sap which is a sure sign eggs have hatched. Finally, when you cut affected fruit you may find Larvae that resembles tiny white maggots inside.

Organic Ways to Deal with Fruit Fly

1. Exclusion

Exclusion is by far the most successful method I've used to combat Fruit Fly. Basically exclusion works by covering the fruit so that the Fruit Fly can't make contact with it at all. I bag all of my Tomato trusses as well as Strawberries and often also Capsicums when the weather gets very warm. I like to use large organza bags as the holes are super fine, they drain well and you can tie them very tightly at the top. You can also buy exclusion bags specifically designed for protection against fruit fly. Netting trees and other plants well can also help to keep them out. Whilst this method may be a little time consuming and aesthetically not ideal, the reward is well worth it. 

2. Sticky Traps and Baits

You can use Sticky Traps in your garden to control Fruit Fly numbers. You hang them from trees or trellises and the fruit flies, attracted to them, will end up stuck there. They won't kill large amounts though and will also potentially trap beneficial insects so they aren't my method of choice. You can also purchase or make your own baits. The bait I make the most consists of a spoon full of Vegemite, a spoon full of sugar and the rind of an orange. Place in a plastic bottle and fill with water about a third of the way. Then cut out a little hole towards the top of the bottle and hang somewhere in the garden, close to plants and trees the Fruit Flies favour. 

3. Keep It Clean

Good garden hygiene is key to keeping Fruit Fly at bay. Don't leave ripe fruit on the vines and clean up any spoiled fruit that falls to the ground. Basically you want to avoid having any rotting fruit or vegetables in the garden at any given time. Any fruit on the vines that looks like it may have been affected by Fruit Fly, remove it and bin straight away.  

4. Companion Planting

Companion Planting can assist in protection against Fruit Flies. Plant Basil, Lavender, Peppermint and Lemon Grass as deterrents. Generally speaking, I find to get this benefit you have to plant in a large amount, not one here and there. 

5. Get the Neighbourhood Involved

 A group effort can make a big difference in keeping Fruit Fly numbers down. Encourage your neighbours to jump on board, especially if they too are growers. Share your knowledge with them. If you are all taking similar measures, together you can make sure everyone reaps the rewards in their harvests!

It's important to note, that research shows the best way to tackle the presence of Fruit Fly in your garden is to use of combination of these methods and not just one.