Formica aserva

Formica aserva is a brood raiding ant that preys on other Formica species. Within its range this species is encountered with some regularity during the summer due to its raids on other ant nests. These raids typically include an active and noticeable foraging column that can be many meters from the raiding colony to the ant nest that is being attacked. Soon to pupate brood that is brought back to the nest is often allowed to eclose and these workers become working members of the F. aserva colony.

Identification
The ventral surface of the head is without erect hairs, the pronotum has fewer than 6 short (less than 0.01 mm) stiff, blunt bristles, and the apex of the petiole is without erect hairs. The petiole is broad and fan-shaped as seen from the front. The central area of the clypeus is striate. (Mackay and Mackay 2002)

Distribution
Canada, Newfoundland west to Yukon. United States: Alaska south to California, east to New Mexico, northeast to New England.

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

Habitat
For New Mexico (Mackay and Mackay 2002) - This species occurs in a wide variety of habitats, ranging from prairies, through sagebrush scrub, juniper forests (Juniperus monosperma), aspen forests (Populus tremuloides) and mixed forests up to fir-aspen-spruce forests, subalpine fir (Abies lasiocarpa) and ponderosa pine. Nests even occur above the tree line.

Biology
In New Mexico (Mackay and Mackay 2002): This species nests in ponderosa pine logs and under stones, and may even construct thatched nests. Brood can be found in nests in early July until early August, reproductives were in nests in August, dealate females were found loose in July and August. This species enslaves F. fusca, F. argentea and F. neorufibarbis, and was found in a F. argentea nest together with F. obtusopilosa. One mixed nest included F. argentea, F. aserva, F. obtusopilosa F. lasioides and Myrmica.

Nomenclature

 *  aserva. Formica sanguinea r. aserva Forel, 1901g: 395 (w.q.) CANADA. Wheeler, W.M. 1913f: 405 (m.). Combination in F. (Raptiformica): Emery, 1925b: 260. Synonym of subnuda: Creighton, 1950a: 469; Wilson & Brown, 1955: 118; Buren, 1968a: 33. [All these authors give subnuda as the senior name but the date of availability of subnuda makes it clear that aserva has seniority: Bolton, 1995b: 191; see also under subnuda.]
 * subnuda. Formica sanguinea subsp. subnuda Wheeler, W.M. 1910g: 570 (w.) CANADA. [First available use of Formica sanguinea subsp. rubicunda var. subnuda Emery, 1895c: 335; unavailable name.] Wheeler, W.M. 1913f: 409 (q.m.); Wheeler, G.C. & Wheeler, J. 1953c: 170 (l). Combination in F. (Raptiformica): Emery, 1925b: 260. Subspecies of sanguinea: Wheeler, W.M. 1913f: 469; Wheeler, W.M. 1917a: 533. Raised to species: Creighton, 1950a: 469. Synonym of aserva: Creighton, 1950a: 469; Wilson & Brown, 1955: 118; Buren, 1968a: 33. [Creighton, Wilson & Brown, and Buren incorrectly make subnuda the senior name but aserva has priority and is therefore the valid name of this taxon: Bolton, 1995b: 204.]