Pseudomyrmex spinicola acacia ants guarding a nest entrance. This species has a painful sting and a much more aggressive temperment than most other Pseudomyrmex, an effective deterrent to large vertebrate herbivores. Chiriqui, Panama
Not all of the thorns on a swollen-thorn Acacia house the ants' larvae, but those that do are heavily guarded. Here, Pseudomyrmex spinicola patrol a nest entrance, ready to use their stings if the photographer approaches too close. Chiriqui, Panama.
Pseudomyrmex pallidus Tucson, Arizona, USA