Fall armyworm on maize: how to spot it and control it

Fall armyworm is a caterpillar that has spread across Africa since 2016 and attacks maize above all. Caught early, it can be kept under control with simple steps. This guide follows the integrated pest management advice of the FAO and CIMMYT.

How to recognise it

• Leaf damage: young caterpillars scrape the leaf surface, leaving thin see-through patches (“windows”). Older ones eat ragged holes in the leaves.
• In the funnel (whorl): wet, sawdust-like droppings in the centre of the plant are a strong sign.
• The caterpillar: a pale upside-down “Y” on the head, and four dark spots in a square near the tail end.
• Eggs: clusters on the leaves, often covered with fine, hair-like scales.

1. Check your field regularly

The FAO advises visiting the field twice a week while the maize is young, when moths lay the most eggs, and once a week or every two weeks later on. Walk through the field and look closely at plants in different parts of it, not only at the edges.

2. Use your fingers before pesticides

Crush egg clusters and young caterpillars by hand when you find them. On a small farm, regular hand-picking can keep numbers low without any spraying.

3. Plant to reduce the risk

• Plant early, and at the same time as your neighbours. Staggered planting gives the pest a constant supply of young maize.
• Keep the field free of weeds and the crop healthy and well fed.
• Push-pull: plant desmodium between the maize rows to repel the moths, and Napier or Brachiaria grass around the field to attract them away.

4. Protect the pest's natural enemies

Natural enemies such as ants, earwigs and tiny parasitic wasps attack fall armyworm eggs and caterpillars. Broad-spectrum insecticides kill them too, which can make the problem worse later. The FAO is clear that relying on pesticides alone does not control fall armyworm sustainably.

5. If you need to spray

If damage keeps spreading despite these steps, get advice before buying a pesticide. Use only products registered for fall armyworm in Nigeria, follow the label for the rate and safety interval, aim into the funnel where the caterpillars feed, and wear protective clothing. Our technical support team can help you decide whether spraying is worth it and what to use.

Growing maize? Read how to grow maize in Nigeria for spacing and fertilizer.