Striped Rice Stem Borer

Chilo suppressalis

1. Identification

• Common name: Striped rice stem borer
• Scientific name: Chilo suppressalis Walker
• Order: Lepidoptera
• Family: Crambidae

2. Pest description

• Adults: Small to medium-sized moths (≈ 18–28 mm wingspan); straw-yellow forewings with dark lines; whitish hindwings.
• Larvae: Whitish to pinkish caterpillars, with a brown head; up to 20–25 mm long; develop inside the stem.
• Eggs: Laid in masses on the leaves, usually on the underside.

3. Main hosts

• Rice.
• Maize.
• Sorghum.
• Various spontaneous grasses in wet areas.

4. Symptoms and damage

• Holes in the young leaves, producing "windowing" (translucent areas resulting from superficial scraping).
• Boring of the stem, with the formation of internal galleries.
• Death of the apical meristem (“dead heart”) in young plants.
• Whitening of the panicles (“white panicles”) due to interruption of the sap flow.
• Significant reduction in productivity and grain quality.

5. Biological cycle

• Winter spent as a larva inside the stem or in crop residues.
• Adults emerge in spring and summer.
• Females lay eggs in masses on the leaves.
• Caterpillars quickly penetrate the stem, where they complete their development.
• Pupation inside the stem or in the soil.
• 2 to 4 generations per year, depending on climatic conditions and the irrigation system.

6. Monitoring

• Observation of windowing on the young leaves.
• Opening of stems to detect galleries and caterpillars.
• Light traps or pheromones to detect adults.
• Assessment of white panicles in the reproductive stage.

7. Management measures

• Cultural: Destruction of crop residues; appropriate water management; crop rotation; use of less susceptible varieties.
• Biological: Conservation of natural parasitoids (e.g.: Cotesia flavipes, Trichogramma spp.).
• Integrated protection: Intervention based on monitoring; application of selective methods compatible with beneficials; avoid late treatments owing to the protection the stem provides to the caterpillars.

Bibliographic references

• EPPO Global Database – Chilo suppressalis.
• CABI Invasive Species Compendium – Chilo suppressalis.
• Pathak, M. D. (1991). Insect pests of rice.
• Heong, K. L. et al. (2015). Rice stem borers: ecology and management.