Desert locust

Definition

A highly polyphagous, swarming acridid grasshopper (Schistocerca gregaria) native to the arid and semi-arid regions of North Africa, the Middle East, and the Indian subcontinent. The species exhibits extreme density-dependent phase polyphenism: isolated individuals develop into a cryptic, sedentary, short-winged solitary phase with rapid reproduction, while crowded conditions trigger a transformation over several generations into a conspicuous, long-winged, highly mobile gregarious phase that forms cohesive swarms capable of transcontinental migration. These swarms represent one of the most destructive agricultural pest phenomena globally, consuming virtually all green vegetation across diverse crops and wild plants.

Etymology

Example

The 2019–2021 East African desert locust upsurge saw swarms originating from the Arabian Peninsula migrate across the Horn of Africa, with individual gregarious adults traveling up to 150 km per day with wind assistance, devastating sorghum, maize, and pasture lands across Kenya, Ethiopia, and Somalia.

Synonyms

• Schistocerca gregaria

Related Terms

• phase polyphenism
• gregarious behavior
• solitary phase
• locust plague
• swarm
• Acrididae
• Grasshopper
• density-dependent plasticity
• outbreak entomology
• pest management

Usage Notes

The common name refers specifically to Schistocerca gregaria and should not be applied to other Schistocerca species (e.g., the Central American locust S. piceifrons) or to non-swarming grasshoppers. Specialists distinguish between 'outbreak' (localized population increase), 'upsurge' (widespread breeding and swarm formation), and 'plague' (multi-year, transcontinental infestation) when describing desert locust population status. The species epithet is frequently misspelled 'gregaria' in older literature; current usage follows Forskål's 1775 original 'gregaria'.