African maize stalk borer

Busseola fusca

1. Identification

• Common name: African maize stalk borer
• Scientific name: Busseola fusca Fuller
• Order: Lepidoptera
• Family: Noctuidae

2. Description of the pest

• Adults: Medium-sized moths (≈ 25–30 mm wingspan); forewings brownish to grey; hindwings paler.
• Larvae: Cream to pinkish caterpillars, with small dark spots; brown head; up to 30–40 mm long; develop inside the stem.
• Eggs: Laid in masses, usually between the leaf sheaths.

3. Main hosts

• Maize.
• Sorghum.
• Other cultivated and wild grasses of lesser importance.

4. Symptoms and damage

• Perforations in young leaves, forming typical “windowing”.
• Perforation and destruction of the apical meristem (“dead heart”).
• Internal galleries in the stem, reducing the transport of water and nutrients.
• Stem breakage and lodging in severe attacks.
• Significant reduction in yield due to reduced ear formation.

5. Biological cycle

• Overwinters as a larva inside the stem or in crop residues.
• Adults emerge in spring and summer.
• Females lay eggs between the leaf sheaths.
• Caterpillars quickly bore into the stem, where they complete their development.
• Pupation inside the stem or in the soil.
• 2 to 3 generations per year, depending on climatic conditions.

6. Monitoring

• Observation of perforations and “windowing” in young leaves.
• Opening of stems to detect galleries and caterpillars.
• Monitoring of adults with light traps or pheromones (where available).
• Historical record of the holding for risk forecasting.

7. Management measures

• Cultural: Destruction of crop residues; crop rotation; staggered sowing; choice of less susceptible varieties.
• Biological: Conservation of natural parasitoids (e.g.: Cotesia sesamiae); use of biological agents where available.
• Integrated protection: Intervention based on monitoring; application of selective methods compatible with beneficials; avoid late treatments due to the protection the stem provides to the caterpillars.

Bibliographic references

• CABI Invasive Species Compendium – Busseola fusca.
• EPPO Global Database – Busseola fusca.
• Kfir, R. et al. (2002). Maize and sorghum stem borers in Africa.
• Van den Berg, J. (2017). Ecology and management of Busseola fusca.