The slave-making ant Protomognathus americanus and its hosts Leptothorax ambiguus, L. curvisponosus, and L. longispinosus nest in tiny preformed cavities found in acorns, hickory nuts, and very small pieces of rotting hardwood lying on the ground. Their favourite nest sites are old acorns which have been partly hollowed out by beetle larvae.
Here we see the interior of an laboratory nest containing a colony of P. americanus. The Protomognathus queen is the large ant in the upper left quadrant. In the centre, a large-headed Protomognathus worker is being fed by a smaller-headed Leptothorax longispinosus slave. The other ants in the photograph are also enslaved L. longispinosus workers. The white, curved things in the photograph are larvae. The three small oval-shaped objects to the right of the queen's head and below her in the photo are eggs.
Protomognathus raids begin when one or several Protomognathus workers leave the nest to search for a host-species target colony. Here three Protomognathus workers are waiting just inside the nest entrance for the return of scouts. Protomognathus workers stand near the nest entrance only when scouts are out. At other times, they remain near the queen.
When a scout returns, she leads a procession of slave-makers and slaves back to the target nest which she has discovered. The procession leader extrudes her stinger and drags it along the substrate while emitting a volatile trail pheromone that the other ants follow.
In this close-up view, a Protomognathus scout leads two reddish L. curvispinosus slaves.
This is a view of a Protomognathus nest after a successful raid. Note the numerous host-species worker pupae piled up along the right and bottom of the picture. At centre right, a Protomognathus worker is perched on an acorn fragment. At centre left, a reddish L. ambiguus slave feeds another Protomognathus worker. The other reddish ants in the photo are other L. ambiguus slaves, while the other black ants are L. longispinosus slaves.
