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
A swollen-thorn Acacia without protective ants is quickly overrun with vines.

Armenia, Belize
A swollen-thorn Acacia without protective ants is quickly overrun with vines.

Armenia, Belize
A basketball-sized carton nest of Crematogaster castanea tricolor in an Acacia tree.

St. Lucia, KZN, South Africa
An arboreal carton nest of Crematogaster castanea tricolor.  This nest is about the size of a softball.  

St. Lucia, KZN, South Africa
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.
Tetraponera clypeata

St. Lucia, KZN, South Africa
Tetraponera clypeata nest inside the hollow thorn of an Acacia tree.  The elongate form of these ants allows them to maneuver in such cramped quarters.

St. Lucia, KZN, South Africa
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.
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.
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.
See photo in original gallery.
all images and text © Alex Wild 2001-2013