Carrot fly

Psila rosae

1. Identification

• Common name: Carrot fly
• Scientific name: Psila rosae Fabricius
• Order: Diptera
• Family: Psilidae

2. Pest description

• Adults 4–5 mm, dark, shiny body, orange head
• Pale-yellow, cylindrical, apodous larvae, feed on the roots
• Brown pupae, formed in the soil
• White, elongated eggs, laid in the soil next to the plants

3. Main hosts

• Carrot
• Parsnip, parsley, celery and other Apiaceae
• Marked preference for carrot crops

4. Symptoms and damage

• Leaves with purple or reddish colouration
• Reduced vigour and slow growth
• Sinuous galleries in the roots, making them unfit for consumption
• Facilitated entry of fungi and bacteria
• Significant economic losses in root crops

5. Biological cycle

• Two to three generations per year
• Adults emerge in spring
• Oviposition in the soil, next to the collar of the plants
• Larvae feed on the roots for 3–4 weeks
• Pupation in the soil, where they can overwinter
• Emergence favoured by moist soils and moderate temperatures

6. Monitoring

• Yellow chromotropic traps for detection of adults
• Observation of symptoms on the leaves and roots
• Root sampling to detect galleries
• Intensive monitoring between April and September
• Recording of favourable conditions (high humidity and mild temperatures)

7. Management measures

• Cultural: crop rotation with non-host species; sowing in ventilated locations; use of insect-proof nets; removal of crop residues; avoiding very early sowing in risk areas.
• Biological: conservation of natural parasitoids and predators; application of entomopathogens in the soil.
• Integrated protection: continuous monitoring; targeted treatments when thresholds are reached; use of traps for population reduction; irrigation management to avoid excess humidity; judicious application of authorised insecticides.

Bibliographic references

• EPPO Global Database – Psila rosae
• CABI Invasive Species Compendium – Psila rosae
• Collier, R. H. (2006). Biology and management of carrot fly
• Finch, S. & Collier, R. (2000). Integrated control of Psila rosae