Western harvester ant

Definition

A medium-to-large seed-harvesting ant, Pogonomyrmex occidentalis (Formicidae: Myrmicinae), native to arid and semi-arid regions of the western United States. Colonies construct conspicuous gravel mounds that can exceed 1 m in diameter, often creating vegetation-free halos that alter local plant community structure. Workers forage collectively for seeds and dead arthropods, and possess a potent, painful sting used in colony defense.

Etymology

Latin occidentalis, 'of the west'; 'harvester' refers to seed-gathering behavior shared with congeners.

Example

In sagebrush steppe, Pogonomyrmex occidentalis mounds can reach densities of 20–40 per hectare, with their foraging ranges collectively removing substantial fractions of annual seed production and creating distinctive bare circles visible from aerial imagery.

Synonyms

• Pogonomyrmex occidentalis

Related Terms

• Harvester ant
• Pogonomyrmex
• Granivory
• seed predation
• mound-building
• Formicidae
• Myrmicinae
• defensive sting
• ecosystem engineering

Usage Notes

Distinguished from the red harvester ant (Pogonomyrmex barbatus) of the southwestern U.S. and Mexico by range and subtle morphological differences; both are sometimes called 'harvester ants' in range management literature. The common name is sometimes applied loosely to any western Pogonomyrmex, but properly refers only to P. occidentalis. Venom contains potent allergens and has caused human fatalities in rare cases of mass stinging events.