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Temporal range: 33.9–0 Ma
Early Oligocene – Recent
Solenopsis geminata
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Solenopsidini
Genus: Solenopsis
Westwood, 1840
Type species
Solenopsis mandibularis (junior synonym of Solenopsis geminata)
218 species
9 fossil species
(Species Checklist)

Solenopsis geminata casent0063125 profile 1.jpg

Solenopsis geminata

Solenopsis geminata casent0063125 dorsal 1.jpg

Specimen Label

Evolutionary Relationships









Austromorium, Monomorium, Oxyepoecus



some Monomorium






Adelomyrmex, Baracidris, Cryptomyrmex

Based on Ward et al., 2014

Solenopsis is a large, cosmopolitan, and taxonomically difficult genus of mostly minute, monomorphic, wholly subterranean species. These minute species frequently live as thief ants within the colonies of other larger species of ants or termites. Some New World species are larger and the workers are polymorphic. These species have colonies that can be very large and the workers are aggressive surface foragers. These ants are commonly referred to as "fire ants" because of the intense, burning sensation caused by their stings. The fire ants are important pest species. (Wheeler and Wheeler 1986)

Photo Gallery


Workers can be separated from similar genera such as Monomorium, Dolopomyrmex, Carebara by the ten segmented antenna and the two segmented antennal club. There are english and spanish keys for the New World thief ants.

Deyrup and Prusak (2008) - Members of the genus can usually be recogniszed by the following combination of character states: 2-segmeneted petiole, 2-segmented antennal club; propodeum lacking spines or angles; petiolar node well developed; head and body shining, localized striae; clypeus longitudinally carinate, with a median, apical marginal seta.

Keys including this Genus

Keys to Subgenera or Species Groups in this Genus

Keys to Species in this Genus


Distribution and Richness based on AntMaps


The thief ants were relatively recently revised (Pacheco and Mackay 2013). This work was an important step forward in our understanding of these small ants. Despite this recent revision there still remains many species that are known only from a few specimens or, if known from more material, are generally poorly known.

Pacheco and Mackay (2013) - The thief ants group of the genus Solenopsis is virtually cosmopolitan throughout the New World. The genus ranges from southern Canada to Argentina. The majority of the species can be found in tropical rain forests, especially in areas of thick leaf litter. Most colonies of the smaller species are found in the soil without an entrance hole, unless nuptial flights are occurring. Occasionally nests are discovered under stones, but are often found while one is excavating the nest of another ant species (Mackay and Mackay 2002). They are considered thief ants because they pilfer the nests of other ants, where they steal brood or food. Some species are considered pests, such as Solenopsis molesta, perhaps the most abundant of the "smaller species." It can be found in parks and residential areas and occasionally is a house pest. Many species can be collected with subterranean baited traps set at least 10 cm down in the soil column. The ecology of most species is virtually unknown.

An apparently undescribed Solenopsis queen attached to a Pheidole tetra queen. Image by Alex Wild.

Alex Wild (March, 2017) - As best as I can discern, this little Solenopsis is undescribed. She was clinging to the petiole of a Pheidole tetra queen at Brackenridge Field Lab, Texas, and remained firmly attached even in ethanol. While similar to Solenopsis phoretica, she differs in the structure of the petiolar process and in the pilosity.



The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • SOLENOPSIS [Myrmicinae: Solenopsidini]
    • Solenopsis Westwood, 1840b: 86. Type-species: Solenopsis mandibularis (junior synonym of Atta geminata), by monotypy.
    • Solenopsis senior synonym of Diplorhoptrum: Mayr, 1862: 751 (see under Diplorhoptrum).
    • Solenopsis senior synonym of Bisolenopsis, Diagyne, Euophthalma, Granisolenopsis, Labauchena, Lilidris, Oedaleocerus, Paranamyrma, Synsolenopsis: Ettershank, 1966: 134.
    • Solenopsis senior synonym of Octella: Taylor, 1991b: 611.
  • BISOLENOPSIS [junior synonym of Solenopsis]
    • Bisolenopsis Kusnezov, 1953d: 9. Type-species: Bisolenopsis sea, by monotypy.
    • Bisolenopsis junior synonym of Solenopsis: Ettershank, 1966: 134.
  • CAREBARELLA [Myrmicinae: Solenopsidini]
    • Carebarella Emery, 1906c: 137. Type-species: Carebarella bicolor, by monotypy.
    • Carebarella senior synonym of Carebarelloides: Ettershank, 1966: 113.
    • Carebarella junior synonym of Solenopsis: implied in Pacheco & Mackay, 2013: 37, 119 (type-species of Carebarella (C. bicolor Emery, 1906c: 138) was transferred to Solenopsis, establishing Carebarella as a junior synonym of Solenopsis).
  • CAREBARELLOIDES [junior synonym of Carebarella]
    • Carebarelloides Borgmeier, 1937b: 236 [as subgenus of Carebarella]. Type-species: Carebarella (Carebarelloides) condei, by original designation.
    • Carebarelloides junior synonym of Carebarella: Ettershank, 1966: 113.
  • DISOLENOPSIS [unavailable name]
    • Disolenopsis Snelling, R.R. 1981: 397, incorrect subsequent spelling of Bisolenopsis: Bolton, 1995b: 22.
  • DIAGYNE [junior synonym of Solenopsis]
    • Diagyne Santschi, 1923c: 268 [as subgenus of Solenopsis]. Type-species: Solenopsis succinea, by monotypy.
    • Diagyne junior synonym of Solenopsis: Ettershank, 1966: 134.
  • DIPLORHOPTRUM [junior synonym of Solenopsis]
    • Diplorhoptrum Mayr, 1855: 449. Type-species: Formica fugax, by monotypy.
    • Diplorhoptrum as genus: Baroni Urbani, 1968: 68; Kutter, 1977c: 98; Bernard, 1978a: 543; Arnol'di & Dlussky, 1978: 539; Collingwood, 1979: 64; Dlussky & Fedoseeva, 1988: 80; Kupyanskaya, 1990: 132; Atanasov & Dlussky, 1992: 167; Dlussky & Radchenko, 1994: 102.
    • Diplorhoptrum subgenus of Solenopsis: Creighton, 1930b: 43; Creighton, 1950a: 233; Smith, M.R. 1951a: 813; Kusnezov, 1956: 27; Kusnezov, 1957a: 273; Kusnezov, 1962b: 160; Smith, M.R. 1967: 358.
    • Diplorhoptrum junior synonym of Solenopsis: Mayr, 1862: 751; Roger, 1863b: 32; Mayr, 1863: 453; Emery & Forel, 1879: 464; Dalla Torre, 1893: 75; Forel, 1915d: 9; Emery, 1922e: 195; Wheeler, W.M. 1922a: 877; Ettershank, 1966: 134; Kempf, 1972a: 232; Bolton, 1987: 285; Bolton, 1994: 106; Bolton, 1995b: 27; Bolton, 2003: 218.
  • EUOPHTHALMA [junior synonym of Solenopsis]
    • Euophthalma Creighton, 1930b: 43 [as subgenus of Solenopsis]. Type-species: Myrmica globularia, by original designation.
    • Euophthalma junior synonym of Solenopsis: Ettershank, 1966: 134.
  • GRANISOLENOPSIS [junior synonym of Solenopsis]
    • Granisolenopsis Kusnezov, 1956: 26 [as subgenus of Solenopsis] (diagnosis in key). Type-species: Solenopsis (Granisolenopsis) granivora, by original designation.
    • [Granisolenopsis also described as new by Kusnezov, 1957a: 277.]
    • Granisolenopsis junior synonym of Solenopsis: Ettershank, 1966: 134.
  • LABAUCHENA [junior synonym of Solenopsis]
    • Labauchena Santschi, 1930d: 81. Type-species: Labauchena daguerrei, by monotypy.
    • Labauchena junior synonym of Solenopsis: Ettershank, 1966: 134.
  • LILIDRIS [junior synonym of Solenopsis]
    • Lilidris Kusnezov, 1956: 26 (diagnosis in key). Type-species: Lilidris metatarsalis, by original designation.
    • [Lilidris also described as new by Kusnezov, 1957a: 274 and Kusnezov, 1958b: 189.]
    • Lilidris junior synonym of Solenopsis: Ettershank, 1966: 134.
  • OCTELLA [junior synonym of Solenopsis]
    • Octella Forel, 1915b: 70 [as subgenus of Oligomyrmex]. Type-species: Oligomyrmex (Octella) pachycerus, by original designation.
    • Octella junior synonym of Oligomyrmex: Ettershank, 1966: 119.
    • Octella junior synonym of Solenopsis: Taylor, 1991b: 611.
  • OEDALEOCERUS [junior synonym of Solenopsis]
    • Oedaleocerus Creighton, 1930b: 43 [as subgenus of Solenopsis]. Type-species: Solenopsis angulata, by original designation.
    • Oedaleocerus raised to genus: Kusnezov, 1957a: 272.
    • Oedaleocerus junior synonym of Solenopsis: Ettershank, 1966: 134.
  • PARANAMYRMA [junior synonym of Solenopsis]
    • Paranamyrma Kusnezov, 1953d: 17. Type-species: Paranamyrma solenopsidis, by monotypy.
    • [Paranamyrma also described as new by Kusnezov, 1954a: 9.]
    • Paranamyrma junior synonym of Solenopsis: Ettershank, 1966: 134.
  • SYNSOLENOPSIS [junior synonym of Solenopsis]
    • Synsolenopsis Forel, 1918b: 155 [as subgenus of Solenopsis]. Type-species: Solenopsis (Synsolenopsis) bruchi (junior primary homonym in Solenopsis, replaced by Solenopsis bruchiella), by monotypy.
    • Synsolenopsis raised to genus: Kusnezov, 1953c: 341; Kusnezov, 1962b: 160.
    • Synsolenopsis junior synonym of Solenopsis: Ettershank, 1966: 134.


  • Arnold, G. 1916. A monograph of the Formicidae of South Africa. Part II. Ponerinae, Dorylinae. Ann. S. Afr. Mus. 14: 159-270 (page 242, Solenopsis in Myrmicinae, Solenopsidini)
  • Ashmead, W. H. 1905c. A skeleton of a new arrangement of the families, subfamilies, tribes and genera of the ants, or the superfamily Formicoidea. Can. Entomol. 37: 381-384 (page 383, Solenopsis in Myrmicinae, Solenopsidini)
  • Bolton, B. 1987. A review of the Solenopsis genus-group and revision of Afrotropical Monomorium Mayr (Hymenoptera: Formicidae). Bull. Br. Mus. (Nat. Hist.) Entomol. 54: 263-452 (page 271, 285, Solenopsis in Myrmicinae, Solenopsis genus group; Solenopsis senior synonym of Diplorhoptrum)
  • Bolton, B. 1994. Identification guide to the ant genera of the world. Cambridge, Mass.: Harvard University Press, 222 pp. (page 106, Solenopsis in Myrmicinae, Solenopsidini)
  • Bolton, B. 2003. Synopsis and Classification of Formicidae. Mem. Am. Entomol. Inst. 71: 370pp (page 218, Solenopsis in Myrmicinae, Solenopsidini)
  • Creighton, W. S. 1930b. The New World species of the genus Solenopsis (Hymenop. Formicidae). Proc. Am. Acad. Arts Sci. 66: 39-151 (page 39, Revision of New World species (out of date))
  • Cresson, E. T. 1887. Synopsis of the families and genera of the Hymenoptera of America, north of Mexico, together with a catalogue of the described species, and bibliography. Trans. Am. Entomol. Soc., Suppl. Vol. 1887: 1-351 (page 262, Solenopsis in Myrmicidae)
  • Dalla Torre, K. W. von. 1893. Catalogus Hymenopterorum hucusque descriptorum systematicus et synonymicus. Vol. 7. Formicidae (Heterogyna). Leipzig: W. Engelmann, 289 pp. (page 75, Solenopsis in Myrmicinae)
  • Dlussky, G. M.; Fedoseeva, E. B. 1988. Origin and early stages of evolution in ants. Pp. 70-144 in: Ponomarenko, A. G. (ed.) Cretaceous biocenotic crisis and insect evolution. Moskva: Nauka, 232 pp. (page 80, Solenopsis in Myrmicinae, Solenopsidini)
  • Emery, C. 1877b. Saggio di un ordinamento naturale dei Mirmicidei, e considerazioni sulla filogenesi delle formiche. Bull. Soc. Entomol. Ital. 9: 67-83 (page 81, Solenopsis in Myrmicidae, Pheidolidae)
  • Emery, C. 1895l. Die Gattung Dorylus Fab. und die systematische Eintheilung der Formiciden. Zool. Jahrb. Abt. Syst. Geogr. Biol. Tiere 8: 685-778 (page 770, Solenopsis in Myrmicinae, Solenopsidini)
  • Emery, C. 1914e. Intorno alla classificazione dei Myrmicinae. Rend. Sess. R. Accad. Sci. Ist. Bologna Cl. Sci. Fis. (n.s.) 18: 29-42 (page 41, Solenopsis in Myrmicinae, Solenopsidini)
  • Emery, C. 1922c. Hymenoptera. Fam. Formicidae. Subfam. Myrmicinae. [part]. Genera Insectorum 174B: 95-206 (page 195, Solenopsis in Myrmicinae, Solenopsidini)
  • Emery, C.; Forel, A. 1879. Catalogue des Formicides d'Europe. Mitt. Schweiz. Entomol. Ges. 5: 441-481 (page 464, Solenopsis in Myrmicinae [Myrmicidae])
  • Ettershank, G. 1966. A generic revision of the world Myrmicinae related to Solenopsis and Pheidologeton (Hymenoptera: Formicidae). Aust. J. Zool. 14: 73-171 (page 81, Solenopsis in Myrmicinae, Solenopsis genus group; Solenopsis senior synonym of Bisolenopsis, Diagyne, Euophthalma, Granisolenopsis, Labauchena, Lildris, Oedalecerus, Paranamyrma and Synsolenopsis)
  • Forel, A. 1893b. Sur la classification de la famille des Formicides, avec remarques synonymiques. Ann. Soc. Entomol. Belg. 37: 161-167 (page 164, Solenopsis in Myrmicinae, Solenopsidini)
  • Forel, A. 1895b. A fauna das formigas do Brazil. Bol. Mus. Para. Hist. Nat. Ethnogr. 1: 89-139 (page 130, Solenopsis in Myrmicinae, Solenopsidini)
  • Forel, A. 1899e. Formicidae. [part]. Biol. Cent.-Am. Hym. 3: 57-80 (page 79, Solenopsis in Myrmicinae, Solenopsidini)
  • Forel, A. 1917. Cadre synoptique actuel de la faune universelle des fourmis. Bull. Soc. Vaudoise Sci. Nat. 51: 229-253 (page 243, Solenopsis in Myrmicinae, Solenopsidini)
  • Hölldobler, B.; Wilson, E. O. 1990. The ants. Cambridge, Mass.: Harvard University Press, xii + 732 pp. (page 16, Solenopsis in Myrmicinae, Solenopsidini)
  • Jaffe, K. 1993. El mundo de las hormigas. Baruta, Venezuela: Equinoccio (Ediciones de la Universidad Simón Bolívar), 188 pp. (page 10, Solenopsis in Myrmicinae, Solenopsidini)
  • Kempf, W. W. 1972b. Catálogo abreviado das formigas da regia~o Neotropical. Stud. Entomol. 15: 3-344 (page 232, Solenopsis in Myrmicinae, Solenopsidini; Solenopsis senior synonym of Diplorhoptrum)
  • Mayr, G. 1865. Formicidae. In: Reise der Österreichischen Fregatte "Novara" um die Erde in den Jahren 1857, 1858, 1859. Zoologischer Theil. Bd. II. Abt. 1. Wien: K. Gerold's Sohn, 119 pp. (page 24, Solenopsis in Myrmicinae [Myrmicidae])
  • Pacheco, J.A. & Mackay, W.P. 2013. The systematics and biology of the New World thief ants of the genus Solenopsis (Hymenoptera: Formicidae). Edwin Mellen Press, Lewiston, New York. 501 pp.
  • Smith, D. R. 1979. Superfamily Formicoidea. Pp. 1323-1467 in: Krombein, K. V., Hurd, P. D., Smith, D. R., Burks, B. D. (eds.) Catalog of Hymenoptera in America north of Mexico. Volume 2. Apocrita (Aculeata). Washington, D.C.: Smithsonian Institution Pr (page 1384, Solenopsis in Myrmicinae, Solenopsidini)
  • Smith, F. 1858a. Catalogue of hymenopterous insects in the collection of the British Museum. Part VI. Formicidae. London: British Museum, 216 pp. (page 177, Solenopsis in Poneridae, Attidae)
  • Smith, F. 1860a. Descriptions of new species of hymenopterous insects collected by Mr. A. R. Wallace at Celebes. J. Proc. Linn. Soc. Lond. Zool. 5(17b)(suppl. to vol. 4 4: 57-93 (page 74, Solenopsis in Attidae)
  • Smith, F. 1861b. Catalogue of hymenopterous insects collected by Mr. A. R. Wallace in the islands of Ceram, Celebes, Ternate, and Gilolo. [part]. J. Proc. Linn. Soc. Lond. Zool. 6: 36-48 (page 48, Solenopsis in Attidae)
  • Smith, F. 1871a. A catalogue of the Aculeate Hymenoptera and Ichneumonidae of India and the Eastern Archipelago. With introductory remarks by A. R. Wallace. [part]. J. Linn. Soc. Lond. Zool. 11: 285-348 (page 333, Solenopsis in Myrmicidae)
  • Snelling, R. R. 1963. The United States species of fire ants of the genus Solenopsis, subgenus Solenopsis Westwood, with synonymy of Solenopsis aurea Wheeler (Hymenoptera: Formicidae). Calif. Dep. Agric. Bur. Entomol. Occ. Pap. 3: 1-15 (page 7, Junior synonym of aurea)
  • Taylor, R. W. 1991b. Nomenclature and distribution of some Australasian ants of the Myrmicinae (Hymenoptera: Formicidae). Mem. Qld. Mus. 30: 599-614 (page 611, Solenopsis senior synonym of Octella)
  • Trager, J. C. 1991. A revision of the fire ants, Solenopsis geminata group (Hymenoptera: Formicidae: Myrmicinae). J. N. Y. Entomol. Soc. 99: 141-198 (page 141, Revision of geminata-group)
  • Westwood, J. O. 1840b. Observations on the genus Typhlopone, with descriptions of several exotic species of ants. Ann. Mag. Nat. Hist. 6: 81-89 (page 86, Solenopsis as genus)
  • Wheeler, G. C. and J. Wheeler. 1986. The ants of Nevada. Natural History Museum of Los Angeles County, Los Angeles.
  • Wheeler, W. M. 1910b. Ants: their structure, development and behavior. New York: Columbia University Press, xxv + 663 pp. (page 140, Solenopsis in Myrmicinae, Solenopsidini)
  • Wheeler, W. M. 1922i. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. VII. Keys to the genera and subgenera of ants. Bull. Am. Mus. Nat. Hist. 45: 631-710 (page 663, Solenopsis in Myrmicinae, Solenopsidini)