Fruit Flies are one of the most common nuisances in the UK, affecting more than 60% of households.  

So if you encounter this annoying problem, you are certainly not alone.

 Although fruit flies are part of the composting process in the sense that they help to break down organic material, you want to minimise numbers as they proliferate quickly.

 Fruit flies are not your common or garden (or house) fly; they do not usually enter the home through the door or window, they come in with the fruit that you buy or get from the garden.

Adult fruit flies lay eggs on the fruit’s skin and these hatch later when the temperature is right. Fruit flies have a strong sense of smell and are attracted by the smell of overripe or rotting organic matter.

The eggs are microscopic, so they’re invisible, until suddenly – they’re not. Obviously, if the eggs are already in fruit skins when added to a composter there’s a chance they might hatch inside it.

There are several steps you can take to minimise the risk.

In the home

• Because fruit flies lay eggs on exposed food, take care to keep food stored in a fridge or lidded containers, not out in the open in fruit bowls.
• Use up ripe fruit and vegetables as soon as possible.
• Compost organic matter quickly as fruit flies are attracted by the smell of decomposing food.
• Keep stored waste in a lidded kitchen caddy. Always keep the lid on your caddy, even between new additions of waste as you are preparing food.

In the compost bin

• In a well-maintained hot composter flies shouldn’t be a problem as high temperatures  destroy the eggs.
•  If there is a problem, add more carbon-rich materials (woody garden waste/shredded paper/cardboard/wood chips), and mix in well so that any food waste is covered.
• Top the contents with a layer of fresh soil.
• Ensure the compost is kept moist but not wet as flies proliferate in wet conditions.
• Wrap food waste in newspaper so it is covered. Lining your kitchen caddy with newspaper is a convenient way to wrap your waste up as you take it to the composter.  
• Bury food waste deeper in the compost so it is not exposed.
•  Ensure the bin has good aeration – stir really well to get air into the mix.
• Try putting the composter in sunlight – flies like a warm but not hot environment.
• Make sure that you always lock the lid securely.
• Take care not to spill any food around the composter.
• Monitor acidity – if you have added a lot of fermented content from a bokashi bin to your composter, add a handful of lime or crushed baked eggshells to neutralise excessive acidic conditions as flies prefer a low (acidic) pH.
• Flies don’t like the smell of certain plants – peppermint in particular – so you could add sprigs of peppermint to your waste and wipe round the compost bin with lavender, lemongrass, eucalyptus and peppermint essential oils.

In the Green Cone

 In the case of the Green Cone Food Waste Digester, no garden waste can be added as the Cone only accepts food waste, so covering with garden and paper waste is not an option.

Because the Cone’s basket is underground, smells are filtered out by the surrounding soil, meaning there is no obvious attraction for ordinary flies. But if fruit fly eggs are already in fruit skins when added to the Cone, they might hatch inside it. Avoid this by following the advice above on preventing infestations in the home.

Also:

•  Freeze your fruit and veg scraps in a plastic bag or container overnight to kill any eggs or larvae before adding them to the Cone.
• Flies don’t like the smell of certain plants – peppermint in particular – so you could add sprigs of peppermint to your waste and wipe round the compost bin with lavender, lemongrass, eucalyptus and peppermint essential oils.
• Add accelerator powder to add more beneficial bacteria to speed up decomposition.
• Remember food waste should never come higher than the top of the Cone’s underground basket; waste should never be above ground level.
• Some people pour hot water into the contents but this will also kill off beneficial bugs so use only as a last resort for severe infestations

 Get trap happy

You could also try a home-made trap that will act as a magnet.

Add an inch of apple cider vinegar to a glass jar with two drops of washing up liquid.

Put a plastic wrap cover over the top of the jar and poke small holes through with a toothpick. Flies are attracted by the smell and can get in but can’t get out.

Remember to change the liquid regularly to keep the fly trap working.