Formica subintegra

Formica subintegra is an obligate slave-maker of species within the Formica fusca group. They are not active outside the nest except during slave-raids and foraging is undertaken entirely by their slaves, which make up 70-90% of the colony (Apple, Lewandowski & Levine, 2014).

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



Biology
The general biology and raiding behavior of Formica subintegra have been studied by Wheeler (1910a) and by Talbot and Kennedy (1940). The latter investigators, by keeping a chronicle over many summers of a population on Gibraltar Island, in Lake Erie, were able to show that raiding is much more frequent in subintegra than in Formica sanguinea. Some colonies raided almost daily for weeks at a time, striking out in any one of several directions on a given day. Occasionally the forays continued on into the night, in which case the subintegra workers remained in the looted nest overnight and returned home the next morning. In other details the raiding behavior resembled that of sanguinea. Subsequently, Regnier and Wilson (1971) discovered that each subintegra worker possesses a grotesquely hypertrophied Dufour's gland, which contains approximately 700 µg of a mixture of decyl, dodecyl, and tetradecyl acetates. These substances are sprayed at the defending colonies during the slave raids. They act at least in part as “propaganda substances” because they evaporate slowly and help to alarm and to disperse the defending workers.

Fungi
This species is a host for the ectoparastic fungus Laboulbenia formicarum (Espadaler & Santamaria, 2012).

Nomenclature

 *  subintegra. Formica sanguinea subsp. subintegra Wheeler, W.M. 1908f: 627 (w.q.) U.S.A. [First available use of Formica sanguinea subsp. rubicunda var. subintegra Emery, 1893i: 648, pl. 22, fig. 3; unavailable name.] Wheeler, W.M. 1913f: 411 (m.); Hung, 1969: 456 (k.). Combination in F. (Raptiformica): Emery, 1925b: 260. Subspecies of sanguinea: Wheeler, W.M. 1913f: 410. Raised to species and material of the unavailable name gilvescens referred here: Creighton, 1950a: 470. See also: Talbot & Kennedy, 1940: 560.