Desert Locust

Adults are large grasshoppers, typically several centimetres long, with appearance and behaviour that differ markedly between phases: solitary-phase individuals are cryptically coloured and behave independently, while gregarious-phase individuals are more brightly coloured, often yellow or pink, and behave and move together in bands or swarms.

Solitary phase

Low-density form; cryptic colouring, avoids other locusts, limited migration.

Gregarious phase

High-density form; brighter colouring, attracted to other locusts, forms bands and swarms.

Hopper band

A cohesive, marching group of wingless gregarious-phase nymphs.

Eggs are laid in pods in moist sandy soil. Nymphs, known as hoppers, develop through several instars over a few weeks and, in the gregarious phase, can form marching bands. Adults are capable of sustained flight over long distances, particularly downwind, allowing swarms to migrate across countries and even seas when winds are favourable.

Breeding accelerates after rains create green vegetation in normally arid breeding grounds, and successive generations under good conditions can drive rapid population growth and a shift from solitary to gregarious behaviour.

Desert locusts feed on an extremely broad range of plants, including many food crops, pasture, and natural vegetation. A large swarm can consume roughly its own combined body weight in vegetation each day, and given the scale of major swarms, cumulative crop losses can be severe.

Cereal crops such as wheat, maize, and sorghum are among the many hosts affected, alongside numerous other food and forage plants across affected regions.

International agencies coordinate desert locust early warning using field surveys, satellite-derived rainfall and vegetation data, and cross-border reporting networks, since breeding conditions and swarm movements frequently span multiple countries. Early detection of hopper bands and small, localized swarms is important because populations can escalate quickly once gregarious behaviour begins.

Because outbreaks are transboundary and can escalate rapidly, desert locust management relies heavily on coordinated monitoring and early, targeted action.

• Support coordinated regional and international early-warning and reporting systems
• Prioritize early detection of hopper bands and small swarms while they remain localized
• Conserve natural enemies and avoid unnecessary broad-area action against solitary, low-density populations
• Collaborate across borders given the migratory, transboundary nature of outbreaks