Formica exsectoides

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Formica exsectoides
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Formicini
Genus: Formica
Species: F. exsectoides
Binomial name
Formica exsectoides
Forel, 1886

Formica exsectoides casent0104768 profile 1.jpg

Formica exsectoides casent0104768 dorsal 1.jpg

Specimen labels


This species nests in large mound nests. It enslaves Formica fusca and Formica subsericea. Colonies can be large, including over 1,600 individual nests. It is extremely aggressive when the nest is disturbed. (Mackay and Mackay 2002)

At a Glance • Polygynous  


Photo Gallery

  • Worker. Photo by Tom Murray.
  • Foraging worker.
  • Myles Standish State Forest, Massachusetts.
  • Wixaboxet, Rhode Island.
  • Haystack Mountain, Massachusetts.
  • A newly established small nest from Ashburnham, Massachusetts. Photo by Tom Murray.


A member of the Formica exsecta group. Large, bicolored (red head and mesosoma, black gaster) ants with a dull surface. The larger workers can be separated as the vertex of the head is concave. The dorsum of the promesonotum is usually without hairs, at least in the largest workers. The propodeum and petiole are often without erect hairs. (Mackay and Mackay 2002)

Keys including this Species


Widespread in United States.

Distribution based on Regional Taxon Lists

Nearctic Region: Canada, United States (type locality).
Neotropical Region: Mexico.

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb


In New Mexico (Mackay and Mackay 2002) - Mountain meadows through juniper woodlands and grasslands, up to ponderosa pine forests.


Formica exsectoides build interconnected networks of nest mounds in forest areas that have a relatively open canopy. A thriving colony can have hundreds of nests, millions of workers and a large number of queens - creating a high abundance of ants in localized areas. Foragers are omnivorous and can fuel their busy foraging activities by collecting large quantities of honeydew. Individual mounds can be quite large, more than a meter high and many meters in length. Some colonies can persist for many decades by annually replacing senescencing queens with newly-mated, highly fecund replacements. Workers adjust and shift brood within and between nest locations, and even form new nests, in response to temperature and food availability. Changes in insolation will prompt moves to more optimal mounds with higher temperatures that facilitate brood development times, and areas that are particularly rich with food resources are often exploited by moving portions of the colony to mounds closer to richer food sources.

Association with Other Organisms

This species is a host for the Microdon fly Microdon abstrusus (a predator) in Maryland (type), Massachusetts, Pennsylvania, Virginia (Thompson, 1981).



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

  • exsectoides. Formica exsectoides Forel, 1886b: xxxviii (w.q.) U.S.A. Emery, 1893i: 653 (m.). Senior synonym of davisi, hesperia: Creighton, 1950a: 513. See also: Wheeler, W.M. 1913f: 481; Smith, D.R. 1979: 1456.
  • davisi. Formica exsectoides var. davisi Wheeler, W.M. 1913f: 396 (in key) (w.q.) U.S.A. [Formica exsectoides subsp. exsectoides var. davisi Wheeler, W.M. 1913f: 484; unavailable name.] Junior synonym of exsectoides: Creighton, 1950a: 513.
  • hesperia. Formica exsectoides var. hesperia Wheeler, W.M. 1913f: 396 (in key) (w.) U.S.A. [Formica exsectoides subsp. exsectoides var. hesperia Wheeler, W.M. 1913f: 484; unavailable name.] Subspecies of exsectoides: Wheeler, W.M. 1917a: 544. Junior synonym of exsectoides: Creighton, 1950a: 513.



  • Creighton, W. S. 1950a. The ants of North America. Bull. Mus. Comp. Zool. 104: 1-585 (page 513, Senior synonym of davisi and hesperia)
  • Emery, C. 1893k. Beiträge zur Kenntniss der nordamerikanischen Ameisenfauna. Zool. Jahrb. Abt. Syst. Geogr. Biol. Tiere 7: 633-682 (page 653, male described)
  • Forel, A. 1886b. Espèces nouvelles de fourmis américaines. Ann. Soc. Entomol. Belg. 30:xxxviii-xlix. (page xxxviii, worker, queen described)
  • Mackay, W. P. and E. Mackay. 2002. The ants of New Mexico (Hymenoptera: Formicidae). Edwin Mellen Press, Lewiston, NY.
  • Nguyen, V., Lilly, B., Castro, C. 2014. The exoskeletal structure and tensile loading behavior of an ant neck joint. Journal of Biomechanics 47: 497-504 (doi:10.1016/j.jbiomech.2013.10.053).
  • 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 1456, see also)
  • Wheeler, W. M. 1913i. A revision of the ants of the genus Formica (Linné) Mayr. Bull. Mus. Comp. Zool. 53: 379-565 (page 481, see also)