The slave-making ants Leptothorax duloticus and Protomognathus americanus and their hosts Leptothorax ambiguus, L. curvisponosus, and L. longispinosus nest in tiny preformed cavities. Most commonly, they nest in old acorns that have been partly hollowed out by beetle larvae.
Here we see numerous acorn fragments lying on the ground. In the centre is an acorn whose shell is intact except for a single small hole. This is a typical ant nest.
Here the acorn has been opened to reveal numerous tiny reddish ants. It is a nest of Leptothorax amiguus.