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Temporal range: 30–0Ma Oligocene
Meat eater ant feeding on honey02.jpg
Meat ant (I. purpureus)
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Dolichoderinae
Tribe: Leptomyrmecini
Genus: Iridomyrmex
Mayr, 1862
Type species
Formica detecta
Smith, 1858
c. 79 extant species
5 fossil species

Iridomyrmex, or rainbow ants (referring to their blue-green iridescent sheen) is a genus of ants in the subfamily Dolichoderinae.[2] There are 79 extant species and 5 fossil species in this genus and they range from China (fossilised species), Australia, New Zealand (introduced), New Guinea, Solomon Islands and New Caledonia.[3]


Unlike other genera in Dolichoderinae, Iridomyrmex ants have the front margin of the clypeus above the mandibles highly modified with convex areas towards the sides and a central projection, which varies from strongly to weakly developed. The compound eyes are relatively high on the head and away from the mandibles.[4][5]


Meat ants swarming

Iridomyrmex ants are generally aggressive to other ants. They form large nests (from several hundred to over 300,000 workers),[5] which limits the number of competing nests that can be formed in a given area. Often, the only neighbouring ant species that can co-exist are those that are of different size or those that forage for food at different times, thus limiting contact with the Iridomyrmex ants. They can be territorial even with ants of their own species but from different nests.[4]

Nests may be above or below ground, with some species such as I. conifer alternating between the two. Meat ants (I. purpureus) are known to create "super-colonies" of many small nests that are connected together, reaching as large as a kilometre or more in length.[5]


Queen digging a hole

Iridomyrmex ants are generally scavengers. Workers of some species will form "highways" to food sources, while workers of other species forage singly. Iridomyrmex are particularly attracted to seeds with elaiosomes. They will collect these seeds and remove the elaiosomes, discarding the seeds afterwards. The seedlings that sprout from these seeds benefit from the aggressiveness of the Iridomyrmex ants, giving them a better chance of survival.[4]

Caterpillars of certain butterfly species have a symbiotic relationship with Iridomyrmex ants. They produce secretions that the ants will feed on. In extreme cases, the ants will carry the caterpillar back to their nests where they will protect it. These ants may also tend to aphids and coccids, collecting nectar when possible.[4]


Some invertebrate species specialise in predation of Iridomyrmex ants. One spider in particular, the cursorial spider Habronestes bradleyi, is a specialist predator against these ants and will use their alarm pheromones that is released during territorial disputes to locate them.[6][7][8] Ground beetles also have been known to create burrows near ant nests and prey on passing workers.[9] The Australian lizard, thorny devil (Moloch horridus) is a sit and wait predator of small ants, primarily on some species of the genus Iridomyrmex.[10]


See also[edit]


  1. ^ Bolton, B. (2014). "Iridomyrmex". AntCat. Retrieved 18 August 2014. 
  2. ^ "Genus: Iridomyrmex". AntWeb. Retrieved 14 October 2013. 
  3. ^ Shattuck, Brian E. Heterick & Steve (2011). Revision of the ant genus Iridomyrmex (Hymenoptera : Formicidae) (PDF). Auckland, N.Z.: Magnolia Press. ISBN 978-1-86977-676-3. Retrieved 5 January 2015. 
  4. ^ a b c d "Genus Iridomyrmex". Australian Ants. CSIRO. 2001. Archived from the original on 9 February 2008. Retrieved 3 February 2015. 
  5. ^ a b c Heterick, B. E.; Shattuck, S. (2011). "Revision of the ant genus Iridomyrmex (Hymenoptera: Formicidae)". Zootaxa 2845: 1–174. 
  6. ^ Herberstein, Marie Elisabeth (2011). Spider Behaviour: Flexibility and Versatility. Cambridge University Press. p. 139. ISBN 9781139494786. 
  7. ^ Capinera, John L. (2008). Encyclopedia of Entomology 4. Springer Science & Business Media. p. 93. ISBN 9781402062421. 
  8. ^ Litwack, Gerald (2010). Pheromones 83. Academic Press. p. 227. ISBN 9780123815330. ISSN 0083-6729. 
  9. ^ Moore, B.P. (1974). "The larval habits of two species of Sphallomorpha Westwood (Coleoptera: Carabidae: Pseudomorphinae)". Australian Journal of Entomology 13 (3): 179–183. doi:10.1111/j.1440-6055.1974.tb02171.x. 
  10. ^ Withers, PC; Dickman, CR (1995). "The role of diet in determining water, energy and salt intake in the thorny devil Moloch horridus (Lacertilia: Agamidae)" (PDF). Journal of the Royal Society of Western Australia, 7 78 (3). Retrieved 4 January 2015. 

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