Carrot flies are a small black fly whose larvae feed on carrot roots. They also attack plants with similar scents such as parsnips, celery and turnips. These pests are attracted by the smell of broken foliage and once they lay eggs, the larvae tunnel into roots, leaving crops inedible.
 

If you’ve noticed your carrots rotting or developing rusty tunnels, carrot fly could be the cause. Left untreated, they can wipe out large amounts of produce in beds, plots and allotments. Protecting crops with carrot fly netting is the most reliable way to reduce damage and keep harvests healthy.
 

Carrot fly netting works by creating a physical barrier that prevents the flies from reaching your plants. The mesh size is small enough to stop even tiny insects while still allowing in light, air and water. Many gardeners also use ultra-fine insect netting and fleece crop covers for added protection against other pests and harsh weather.
 

Another method is to use a carrot fly fence around your bed. Since carrot flies cannot fly higher than around 1 metre, these fences stop them reaching plants while also containing scents that would otherwise attract the pests.
 

For best results, set up your netting or fences early in the season before flies are active. Secure them with aluminium hoops, bamboo canes or support frames, fixing the netting in place with clips or ties to create a tight seal.
 

Frequently Asked Questions

How does carrot fly netting work?
Carrot fly netting has very fine mesh (0.27mm × 0.88mm), much smaller than standard insect netting. It blocks flies from reaching crops and reduces the carrot scent that attracts them.

What height does the barrier need to be?
Carrot flies rarely fly above 1 metre. Using a carrot fly fence or netting supported by hoops at least this height will stop most attacks.

When should I put netting in place?
Set it up before planting or as soon as seedlings appear. Flies are most active in spring and late summer, so cover plants during these times.

How do I use carrot fly netting?
You can secure it with 16mm or 19mm aluminium poles and clips, or with bamboo canes using 13mm clips. Ensure the netting is sealed at ground level to block entry.

Can carrot fly netting be reused?
Yes. Made from UV-stabilised material, it can last for several seasons if stored dry and rolled after use.

What other crops should I protect?
Parsnips, celery, parsley and turnips are also vulnerable to carrot fly damage and benefit from netting.

Can I combine it with other covers?
Yes. Many gardeners layer with fleece covers for frost protection or use insect netting for wider pest control.