In exchange for protection, swollen-thorn Acacia trees provide Pseudomyrmex ants with food and shelter.  Here an ant feeds from a leaf nectary. (Pseudomyrmex spinicola)

Chiriqui, 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.
Cutting open the surprisingly soft flesh of an Acacia thorn reveals larvae and pupae of the Pseudomyrmex spinicola acacia ant.  

Chiriqui, Panama.
Friend or Foe? Two Pseudomyrmex spinicola acacia ant nestmates evaluate each other at the nest entrance. 

Panama City, Panama
Pseudomyrmex spinicola workers harvest Beltian bodies on an Acacia tree. The tree and the ant are locked into relationship where the survival of both partners depends on the other.  The ants provide the Acacia with protection from herbivores and from competing plants, while the tree provides the ants with food and shelter.  

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 spinicola acacia ant, at the entrance to a thorn nest.

Chiriqui, Panama
Portrait of a mutualism: a swollen-thorn Acacia with the ants that protect it.  The hundreds of thorns on a mature tree can house colonies of up to 20,000 ants.

Chiriqui, Panama
Pseudomyrmex spinicola acacia ant, at the entrance to a thorn nest.

Chiriqui, Panama
Pseudomyrmex spinicola acacia ant, at the entrance to a thorn nest.

Chiriqui, Panama
Pseudomyrmex spinicola acacia ant, at the entrance to a thorn nest.

Chiriqui, Panama
See photo in original gallery.
all images and text © Alex Wild 2001-2013