On my recent visit to the coastal forests of Kwazulu-Natal I noticed basketball-like growths on many of the Acacia trees. In North America, any large gray ball you see hanging off a tree branch is liable to be a hornet’s nest. In South America, it’s probably a carton nest of fierce little Azteca ants. The equivalent in South Africa? I didn’t know.
A little bit of poking around in the acacias revealed the culprit. It was Crematogaster tricolor, an orange ant about half a centimeter long:
They didn’t appreciate the disturbance, apparently, because they came after me without hesitation: