Slave-making ant (Protomognathus americanus)

Slave-making ant, preserved specimen
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Slave-making ant fact file

Slave-making ant description

GenusProtomognathus (1)

Protomognathus americanus is a small, blackish-brown ‘slave-making ant’, an ant which enslaves ants of other species in order to provide workers for its own colony (3) (4). One distinguishing feature of this slave-making ant are the deep grooves on each side of the head. The antennae are folded into these grooves to avoid damage while fighting other ants (3).

Male weight: 0.12 - 0.19 mg (2)
Female weight: 0.39 - 0.58 mg (2)

Slave-making ant biology

Protomognathus americanus queens (winged females) and males mate in July, following which the female sheds her wings and crawls about on the ground in search of a nearby nest belonging to one of three species of ant: Leptothorax ambiguus, Leptothorax curvispinosus or Leptothorax longispinosus. Once a nest has been located, the queen proceeds to invade the nest, savagely ridding it of Leptothorax ants by seizing each worker ant by its antennae, dragging the ant outside the nest, and flinging it to one side. The queen moves rapidly, to avoid attacks from the Leptothorax workers (3).

After the queen has ransacked the colony in this manner for a while, the remaining Leptothorax workers and queen panic and desert the nest, leaving behind their larvae and pupae. As these Leptothorax young develop, they recognise the female Protomognathus americanus ant as their queen and serve her accordingly, carrying out the necessary foraging, nest-building and caring for the new queen’s own brood (3).

When the new Protomognathus americanus queen’s own brood develop they are not like traditional worker ants, as the Leptothorax slaves adopt this role. Instead, they remain in the nest while the slaves feed them by regurgitating food into their mouths and periodically go in search of a new Leptothorax nest to raid, in order to bring back Leptothorax larvae and pupae to replenish the slave work force. If asingle Protomognathus americanus ant locates a Leptothorax nest it may attempt to overtake it, but if unsuccessful, the ant will return to the home nest and lay a chemical trail to entice a larger group of ants towards the Leptothorax nest (3).


Slave-making ant range

A fairly widespread species of slave-making ant, Protomognathus americanus occurs in eastern North America, from Ontario south to Virginia and west to Ohio (3).


Slave-making ant habitat

Protomognathus americanus is typically found in mixed deciduous forest (5) (6).   


Slave-making ant status

Protomognathus americanus is classified as Vulnerable (VU) on the IUCN Red List (1).

IUCN Red List species status – Vulnerable


Slave-making ant threats

While Protomognathus americanus is considered threatened by the IUCN Red List (1), it is not clear what threats this ant faces.


Slave-making ant conservation

There are no known conservation measures currently in place for Protomognathus americanus.


Find out more

To learn more about the conservation of ants and other insects see:



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This species information was authored as part of the Arkive and Universities Scheme.


Deciduous forest
Forest consisting mainly of deciduous trees, which shed their leaves at the end of the growing season.
Stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
Stage in an insect’s development when huge changes occur, which reorganise the larval form into the adult form. In butterflies the pupa is also called a chrysalis.


  1. IUCN Red List (October, 2010)
  2. Herbers, J.M. and Stuart, R.J. (1998) Patterns of reproduction in slave-making ants. The Royal Society, 265: 875-887.
  3. Hölldobler, B. and Wilson, E.O. (1990) The Ants. Harvard University Press, Cambridge, Massachusetts.
  4. Preston-Mafham, R. and Preston-Mafham, K. (1993) The Encyclopedia of Land Invertebrate Behaviour. MIT Press, Cambridge, Massachusetts.
  5. Achenbach, A. and Foitzik, S. (2009) First evidence for slave rebellion: enslaved ants systematically kill the brood of their social parasite Protomognathus americanus. Evolution, 63, 1068-1074.
  6. Herbers, J.M. and Foitzik, S. (2002) The ecology of slavemaking ants and their hosts in north temperate forests. Ecology, 83, 148-163.

Image credit

Slave-making ant, preserved specimen  
Slave-making ant, preserved specimen

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