How to fight against the carrot fly?

Are your carrot plants looking sad? Are the roots hollowed out and blackened? It’s probably the carrot fly!

Find out how to fight this vegetable garden pest.

Read also :

  • Growing carrots well
  • Treating the onion fly

Psila rosae, the carrot fly

This flying insect belongs to the psilidae family. This fly has a slender figure resembling a wasp.

Its body is black, its head is brown, its legs are yellow and its wings are a translucent pale yellow.

It's the larva that's causing the problem in the vegetable garden! Measuring up to 1cm long, it is creamy yellow in color. The problem ? She particularly appreciates carrot roots ...

© Rasbak, Wikimedia Commons

Life cycle

In spring, flies lay eggs near young carrot plants. Each female lays about 50 eggs in the soil. Once the egg has hatched, the larva burrows into the earth to feed on the roots. They even end up digging galleries there, which considerably weakens the plant. The maggot will then transform into a pupa to pupate. After a short month, the pupa gives way to an adult insect.

Each year, two to three generations follow one another. In winter, the pupae enter diapause underground. The insects will then emerge from the ground the following spring, when the temperatures will be milder.

Symptoms and damage to the vegetable garden

By digging directly into the carrots, the crop is endangered, but especially the harvest! Your plants will then be weakened, wilted and the leaves will turn yellow.

In the event of a strong attack, the plants will perish and the harvest will be compromised. By pulling your carrots, you will then see the roots hollowed out and marked by black trails.

Preventive techniques against carrot maggot

Crop rotation:

As this insect spends the winter underground, near carrot plants, it is essential to move the host plant. If you have already suffered an attack from this pest, consider removing your carrots significantly during the next sowing. Indeed, there could be pupae underground, even if you think you have eradicated them all.

The insect net:

In prevention, install an insect net which will serve as a fly barrier. Thus, they will not be able to come and lay at the base of the carrots. The fly flies at a height of 60cm maximum, consider using a net of the same height.

Culture associations:

Certain plants have a repellent effect on certain insect pests.

This is the case with alliates like onion, leek and garlic, which repel the carrot maggot. A service rendered by the latter which keeps the fly away from the onion. Better to plant these two next! You can also install wormwood nearby, its smell repels the fly.

Coffee grounds :

When sowing, add coffee grounds. The strong scent repels flies, while being a fertilizer of choice!

Lavender mulch:

While we love lavender to the point of making scent sachets, the carrot fly doesn't. When transplanting, place a lavender mulch at the base of the carrots, the fly will not come and lay there.

Natural treatments

Are your carrots already under attack? Remember to remove any affected carrots and burn them. Here are two environmentally friendly ways to fight.

Glue bands:

The same color as carrots, these strips work as a trap for flies. Place them at flight height, so that they can be easily attached. This technique is a good complement to eradicate them. However, it will not be enough to eradicate them on its own, especially if the attack is significant.

Garlic or onion infusion:

Also with the aim of removing these pests from the garden, prepare an infusion of garlic.

  1. Boil a liter of rainwater or filtered water
  2. Add 100g of crushed garlic
  3. Keep boiling for 15min
  4. Cover and let infuse for 12 hours
  5. Pour the preparation into a sprayer using a Chinese to filter it

You can keep this decoction in the fridge for 10 days. To use it, simply spray it on the plants concerned.

Video: Fly Tying a Carrot Nymph by Mak (June 2021).