Formica obscuriventris

This species nests under logs or stones, usually partially covered with thatch.

Distribution
Southern Canada and New England southward to Virginia and thence westward to the Pacific.

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

Biology
Syrphidae in the genus Microdon are predators on ant brood within the nest.

Nevada, Wheeler and Wheeler (1986) - Our 48 records are widely scattered in that part of the state north of the Hot Desert boundary (with 1 exception); they represent 39 localities; 5,600-10,000 ft. Nine of these records were from the Cool Desert, 8 from the Pinyon-Juniper Biome, 6 from the Coniferous Forest, and 1 from the Alpine Biome. Our remarks about the nest of Formica obscuripes apply to F. obscuriventris but the latter seemed to produce more variants. The same applied to behavior, except that F. obscuriventris was more prone to send out foraging columns. Formica obscuriventris was found tending the aphid, ''Aphis filifoliae. & P. (Homoptera: Aphididae; det. L.M. Russell), on Pinus monophylla at Lehman Caves Nat. Mon., White Pine Co., 6,800 ft.

Nomenclature

 *  obscuriventris. Formica truncicola var. obscuriventris Mayr, 1870b: 951 (w.) U.S.A. Wheeler, W.M. 1913f: 446 (q.m.). Subspecies of rufa: Mayr, 1886d: 426; Emery, 1893i: 649; Wheeler, W.M. 1908g: 408; Creighton, 1940a: 1; of truncicola: Wheeler, W.M. 1913c: 116; Wheeler, W.M. 1913f: 445; Wheeler, W.M. 1917i: 464. Raised to species: Creighton, 1950a: 493. Senior synonym of dryas: Wheeler, W.M. 1913f: 446; of gymnomma: Creighton, 1950a: 493. Current subspecies: nominal plus clivia.
 * dryas. Formica dryas Wheeler, W.M. 1905c: 268 (w.q.) U.S.A. Junior synonym of obscuriventris: Wheeler, W.M. 1913f: 446.
 * gymnomma. Formica dryas var. gymnomma Wheeler, W.M. 1905c: 269 (w.) U.S.A. Subspecies of rufa: Creighton, 1940a: 3. Junior synonym of obscuriventris: Creighton, 1950a: 493.