Formica perpilosa

Nests are found in the soil, with the entrance surrounded by a small mound. It also nests at the base of desert plants, especially grass clumps, in areas of fine sand to loam. It occasionally nests under stones or pieces of wood.

Identification
The clypeus is usually concave or notched and it is an abundantly hairy, black (gaster) and red (head and mesosoma) ant. Most surfaces are moderately shining, including the gaster. It is difficult to place this species in a species complex, and it is presently considered to be a member of the neogagates group, but it doesn’t seem to be closely related to the others in the complex. It was previously considered to be a member of the sanguinea group, based on the notched clypeus. (Mackay and Mackay 2002)

Distribution
Canada, Alberta. United States: Wyoming south to Texas, west to California. Mexico: Chihuahua, Coahuila.

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

Habitat
In New Mexico (Mackay and Mackay 2002) - Chihuahuan Desert (mesquite woodlands, playas), especially common in loose sand, up to foothill meadows and low elevation forests (pinyon-juniper) (below 1850 meters), riparian (cottonwoods, sycamore forests). It is abundant in urban environments.

Biology
It is preeminently a species peculiar to irrigated lands and river bottoms in the deserts of the southwest. There it nests in rather populous colonies about the roots of bushes or trees, often forming obscure craters or low mound nests ... I have never found it nesting under stones. It is a very active and aggressive ant (W.M. Wheeler, 1913).

For New Mexico (Mackay and Mackay 2002) - This is one of the few species of Formica, which occurs in the Chihuahuan Desert, especially in sandy soils. It is also common in lawns in urban environments. Reproductives were found in nests in July, flights occurred in July, dealate females were found during July. Workers forage on the flowers of Yucca elata. This species apparently does not enslave other species of Formica. It is the host of the cricket Myrmecophila sp. It may be an important predator of the boll weevil. This species shows division of labor, and the workers undertake 38 different behavioral acts.

Nevada, Wheeler and Wheeler (1986) – F. perpilosa presents a seeming paradox in Nevada: it has been found only within the boundaries of the Hot Desert, but it cannot be classed as a Hot Desert ant, because it occurs only near streams and other well-watered places. It is our only truly riparian species. Our 16 records are from 8 localities, all in the southern part of the state. We ourselves have found it only once: in Beatty, in a gravel sidewalk beside a hedge which bordered a tree-filled lawn. The low messy crater was 40 cm in diameter, with numerous entrances 6-12 mm in diameter. The workers moved swiftly. Elasmosoma vigilans Ckll. (Hymenoptera: Braconidae; det. P.M. Marsh) was collected at Las Vegas by D.F. Zoller, who noted that the wasps were darting at the ants. This braconid is known to be an ant parasitoid.

Nomenclature

 *  perpilosa. Formica perpilosa Wheeler, W.M. 1913f: 421 (w.q.m.) U.S.A. [First available use of Formica fusca subsp. subpolita var. perpilosa Wheeler, W.M. 1902b: 141; unavailable name.] Combination in F. (Raptiformica): Emery, 1925b: 259.