Governments are struggling to tackle a serious pest that is destroying maize crops as it spreads rapidly across Africa. According to the Centre for Agriculture and Biosciences International (Cabi), this pest, the fall armyworm caterpillar, threatens farmers' livelihoods in the region. They warn that the creature, a native of the Americas, not Africa, may now establish itself in that continent and spread to Asia and the coast of the Mediterranean Sea.

In the US, fall armyworms tend to arrive in the country in autumn, hence the name “fall”. The caterpillars are called armyworms, because they hey “march” across the landscape like an army, eating their way through any vegetation they come across. Once the food supply in an area is exhausted—this might only take a few days—the entire army moves on to the next available source, travelling in the cool of the night. Though the caterpillar mostly damages maize, other crops such as rice, soya beans and cabbage have also been affected by the infestation in Africa.

Scientists think that the caterpillar, or its eggs, may have accidentally arrived in Africa with imported produce. The adult moths are known to be able to fly long distances. Their eggs are therefore laid over a large area, causing the species to multiply rapidly and spread widely.