Monomorium floricola ranks among the most traveled of all ants. This diminutive species has spread with human commerce to nearly every lowland tropical region. Here, a worker tends to a mealybug in Panama. Isla Contadora, Panama
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.