Fall armyworm
A fast-spreading caterpillar that eats maize leaves and shoots, and also attacks many vegetables, leaving ragged holes and sawdust-like droppings.
Also known as: FAW, Spodoptera frugiperda
Symptoms and identification
Small windowed patches, then ragged holes in leaves, and sawdust-like droppings in the whorl of maize. The caterpillars are green to brown with a pale inverted Y on the head and four dark dots on the second-to-last body segment. They also bore into cobs and fruit.
Causes
Moths fly long distances and lay egg masses on leaves. The pest is active in warm weather, breeds all year round in tropical regions and has spread through Africa and Asia in recent years.
Organic treatment
Hand-pick egg masses and young larvae and crush them. Pour a pinch of dry sand, wood ash or a neem or Bt spray into the whorl of young maize. Treat early, while caterpillars are small.
Prevention
Plant early and at the same time as neighbours, inspect young plants twice a week from seedling stage, and keep field edges free of weeds. Encourage natural enemies such as wasps, ground beetles and birds.
Chemical treatment (use with care)
Use an insecticide labelled for fall armyworm on that crop, following local agricultural advice, and rotate products to slow resistance.