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Past Articles Library | Organic Pest Control | Carrot Rust Fly Maggots


(Psila rosae)

Carrot Rust Fly produce creamy white larvae that tunnel into roots of susceptible plants, carrots being one of them, and cause stunted growth, and ruined crops.



The adults are shiny, metallic, greenish-black flies about 1/4 inch (6 mm) long, with yellow legs and head. Larvae are creamy white, tapering maggots found in tunnels in roots.



Adults emerge in mid-April to May to begin laying eggs in the soil close to plants. Eggs hatch in 7 to 10 days. The small maggots burrow in roots for 3 to 4 weeks, then pupate. They can have two or three generations per year. The first generation adults are active from mid April to June. Larvae feed on roots starting in May and June with the subsequent second generation adults emerging in August and September. Late second and early third generation adults are active at the same time with the second generation adults lasting into October. Crop damage accumulates over time.




Carrot, celery, parsley, parsnip, dill, caraway, and fennel.




The root maggots eat fine root hairs, then tunnel through the roots. The tunnels are filled with rusty brown castings. Plants are stunted or killed, and root crops are deformed and ruined. Injuries to the roots can then allow disease organisms to enter. After harvest, maggots feed in stored roots.




1. To provide excellent protection, cover seed beds with Floating Row Covers before seedlings emerge, and make sure to bury the edges under the soil and leave crop covered until harvest.

2. Avoid leaving carrots in the ground over winter. Clean up and discard any carrots that may still be around, and any other plants that carrot rust fly like which are: celery, parsley, parsnip, dill, caraway, and fennel.

3. Sow midseason carrots after the first egg-laying period is over.

4. Harvest roots early to avoid other generations.


Rotate other crops for a few seasons and then start monitoring with yellow sticky traps to see how the adult population is doing. If you see a dramatic decrease then you can start planting carrots again with these precautions in mind:

1. Try growing the resistant variety `Flyaway" carrot.

2. Use Floating Row Covers before seedlings emerge. This can provide excellent protection. Make sure to bury the edges under soil, and leave the crop covered until harvest. This won't allow the adults to lay their eggs, and will really help the problem. This can be done only after any current infestations have been cleaned up. To put floating row covers over infested soil, will only make things worse.

3. Wait and late-plant (after mid-June) to reduce severity of attacks.

4. Continue to rotate your plants.

5. Drench the soil with parasitic nematodes.

6. Plant carrots in raised beds or containers with fresh soil every year and monitor constantly with sticky traps.

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Keep Seedlings Moist

When you have just planted seeds, keep the soil moist until germination.

If the soil dries out, the seeds will die.

After germination, allow the soil to dry out a bit between waterings, but keep a close eye on the seedlings until they are well established.

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