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What Is a Carrot Fly?

B. Chisholm
B. Chisholm

The carrot fly, or psila rosae are a garden pest that attacks mainly carrots, parsnips, celery and parsley. It is their larvae which cause the damage, beneath the soil, making it difficult to detect their presence before pulling up the crop, although the leaves above ground may become discolored. The carrot fly may have up to three life cycles each season.

The carrot fly lays its eggs in the soil next to the growing carrots. The first laying occurs in early spring and the larvae hatch within ten days. Initially they feed on the roots of the carrot but then burrow into the actual vegetable, creating little burrows which then allow mold to enter and make the whole carrot rotten. The larvae then develop into the tiny black carrot fly which flies very close to the ground. The whole process is repeated midsummer, and again in late autumn and the larvae remain in the ground, overwintering, during the winter months.

The carrot fly, or psila rosae are a garden pest that attacks mainly carrots, parsnips, celery and parsley.
The carrot fly, or psila rosae are a garden pest that attacks mainly carrots, parsnips, celery and parsley.

The main problem with carrot fly is that it often goes undetected until the vegetable is pulled up to eat. Many methods to prevent an infestation have been tried. The carrot fly is attracted by the scent of carrots, which it can detect from a large distance away. To prevent attracting them to the crop, carrots should be well spaced when planting, thus minimizing the need for thinning out. When harvesting the crop, carrots should be pulled at dusk, preferably on a windless evening, as the carrot flies are only active during the day.

Due to the fact that the fly can only fly about two feet (61 cm) from the ground, covering the plants with a protective mesh or two-foot high barrier around them, or planting them in pots which are kept high on a table, may be effective. Timing the planting of carrots to miss the three active periods of the carrot fly larvae may also help. Various methods of inter-planting with other crops, such as onions, have been suggested, but the efficacy of this has not been proven. It is thought that planting strong-smelling plants may make it more difficult for the fly to detect the presence of carrots.

When carrots have been attacked by the larvae, the leaves may turn an orange color, and then yellow. In many cases, though, the effect is only seen on the carrot, when picked. The carrot may be disfigured and the end often has little holes, or burrows, in it and may have turned black, due to mold. Some carrot varieties are more resistant to carrot fly than others.

Frequently Asked Questions

What is a carrot fly and why is it a problem for gardeners?

A carrot fly is a small, dark-bodied insect that poses a significant threat to carrot crops. It lays eggs near the base of the carrot plant, and the emerging larvae burrow into the roots, causing damage that can lead to secondary infections. Gardeners dread this pest because it can decimate a crop, making the carrots inedible and reducing yields.

How can you identify damage caused by carrot flies?

Damage from carrot flies is identified by the telltale signs of rusty brown, tunnel-like markings on the carrot roots. Affected carrots may also have a stunted or forked growth. Above ground, the foliage can turn a reddish color and wilt, indicating that the larvae are feeding below. Early detection is crucial to manage the infestation effectively.

When are carrot flies most active, and how does this affect their control?

Carrot flies are most active during their two peak periods of activity: late spring and mid-summer. They are particularly drawn to the scent of carrots during thinning. Timing is critical for control measures; barriers and protective coverings should be in place before these periods to prevent the flies from laying eggs near the carrot plants.

What are some effective methods to prevent carrot fly infestations?

Preventing carrot fly infestations involves several strategies. Using fine mesh barriers or fleece to cover crops can physically block flies from reaching the plants. Crop rotation and avoiding thinning can reduce the scent that attracts flies. Companion planting with strong-scented plants like onions can also mask the smell of carrots, deterring the pests.

Can carrot flies affect other plants besides carrots?

Yes, carrot flies can affect a range of plants in the Apiaceae family, not just carrots. They are known to target parsnips, celery, parsley, and celeriac as well. The larvae can cause similar damage to these related crops, making it important for gardeners to protect a variety of plants from this pest.

Are there any natural predators that can help control carrot fly populations?

Natural predators such as ground beetles, rove beetles, and parasitic wasps can help control carrot fly populations by preying on the larvae and eggs. Encouraging biodiversity in the garden by providing habitats for these beneficial insects can enhance their effectiveness in keeping carrot fly numbers in check without the need for chemical interventions.

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    • The carrot fly, or psila rosae are a garden pest that attacks mainly carrots, parsnips, celery and parsley.
      By: dima_pics
      The carrot fly, or psila rosae are a garden pest that attacks mainly carrots, parsnips, celery and parsley.