Formica difficilis

Distribution
This taxon was described from the United States.

Nomenclature

 *  difficilis. Formica rufa subsp. difficilis Emery, 1893i: 651, pl. 22, figs. 9, 14 (w.q.m.) U.S.A. Wheeler, G.C. & Wheeler, J. 1953c: 164 (l.). Raised to species: Wheeler, W.M. 1904e: 305; Wheeler, W.M. 1904f: 348. Senior synonym of consocians, habrogyna: Cole, 1943a: 389.
 * consocians. Formica difficilis var. consocians Wheeler, W.M. 1904f: 371 (w.q.m.) U.S.A. Junior synonym of difficilis: Cole, 1943a: 389.
 * habrogyna. Formica habrogyna Cole, 1939: 413, figs. A-D (w.q.) U.S.A. Junior synonym of difficilis: Cole, 1943a: 389.