Swollen thorn acacia trees pay their ant guardians with nectar. Here, a Pseudomyrmex peperi worker feeds from a nectary. Cayó District, Belize.
A Pseudomyrmex peperi acacia ant attacks a photographer who has brushed up against her tree. Note the standard ant stinging technique of anchoring with the mandibles for leverage to plant the stinger. Cayó District, Belize.
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
