Citrus leafminer

Phyllocnistis citrella

1. Identification

• Common name: Citrus leaf miner
• Scientific name: Phyllocnistis citrella Stainton
• Order: Lepidoptera
• Family: Gracillariidae

2. Pest description

• Adults: small moths with a 2.5–4 mm wingspan; narrow, silvery forewings, with metallic reflections; heavily fringed hindwings.
• Larvae: apodous, very small, yellowish-green in colour; they develop inside young leaves, forming very fine serpentine mines.
• Pupae: form inside the mine, usually in a pupal chamber near the leaf margin, which is rolled up.
• Eggs: laid singly on the underside of young leaves, especially on new shoots.

3. Main hosts

• Citrus: orange tree, tangerine tree, lemon tree, lime tree, grapefruit tree.
• Other Rutaceae may occasionally be affected.
• Young shoots and tender leaves are the most susceptible.

4. Symptoms and damage

• Very fine and shiny serpentine mines, usually on the underside of the leaves.
• Curling and deformation of young leaves due to larval activity.
• Partial necrosis of the mined zones.
• Reduction of shoot growth and delay in plant development.
• In severe attacks, strong reduction of the photosynthetic area and greater susceptibility to secondary infections (e.g.: Pseudomonas syringae).
• Significant impact on nurseries and young citrus orchards.

5. Biological cycle

• Rapid cycle, which can be completed in 2–3 weeks under favourable conditions.
• Eggs hatch in a few days; larvae develop in 3 instars inside the mine.
• Pupation inside the mine, usually near the leaf margin.
• Adults emerge throughout the year in warm regions; flight peaks in spring and summer.
• High number of annual generations, especially in greenhouses and subtropical climates.

6. Monitoring

• Direct observation of serpentine mines on young leaves.
• Counting mined leaves on new shoots.
• Pheromone traps for detection and tracking of adult flights.
• Intensive monitoring in nurseries and young citrus orchards.

7. Management measures

• Cultural: removal of heavily attacked shoots; avoiding excessive pruning that stimulates young sprouting; promoting good canopy ventilation.
• Biological: conservation of natural parasitoids (e.g.: Ageniaspis citricola, Cirrospilus spp., Pnigalio spp.), which are fundamental in natural control.
• Integrated protection: regular monitoring, intervention only when necessary, application of measures that reduce larval survival inside the mines and rotation of modes of action.

Bibliographic references

• EPPO Global Database – Phyllocnistis citrella.
• CABI Invasive Species Compendium – Phyllocnistis citrella.
• Heppner, J. B. (1993). Citrus leafminer, Phyllocnistis citrella, in Florida. Tropical Lepidoptera, 4, 49–64.
• García-Marí, F. (2010). Plagas de los Cítricos. Generalitat Valenciana.
• Uygun, N., & Karaca, I. (2000). Biology and control of the citrus leafminer. Integrated Pest Management Reviews, 5, 1–22.