Formica exsectoides

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)

Identification
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)

Distribution
Widespread in United States.

Distribution based on Regional Taxon Lists
Nearctic Region: Canada, United States. Neotropical Region: Mexico.

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

Biology
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.

Nomenclature

 *  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.