Polyergus oligergus Trager
Polyergus oligergus, full face view of a worker (click image to enlarge).
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Polyergus oligergus,profile view of a worker (click image to enlarge).
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Polyergus workers can be easily recognized by their large size (approximately 4.0 - 7.0 mm long), yellowish-red to dark reddish-brown coloration, and possession of sickle-shaped (falcate) mandibles with minute serrations on inner border.

Polyergus species are obligatory or true slave-making ants. In nest founding, the female enters a nest of the host species, eventually kills the rightful queen, and uses the host workers to tend her brood. Polyergus colonies conduct slave raids on nests of various species of Formica, and workers of the host are taken and used by the Polyergus colony to feed and rear the brood and excavate the nest. Polyergus workers are incapable of surviving without slaves. In laboratory colonies, a colony without slaves will starve to death even when plentiful food is available. (Hedlund, 2007; King and Trager, 2007)

Overall length approximately 6.5 mm. Color, yellowish-brown with the posterior border of the last 4 segments of the gaster and the appendages infuscated. Head, alitrunk, petiole and gaster shining (except meso- and metapleura). Head 1.06 times longer than wide, cheeks slightly concave, sides of head converge above eyes, occipital border feebly emarginate. Eye convex, longer than wide, situated more than its greatest diameter from the mandibular base. Antennal scape long, 1.13 times length of interocular distance, and gradually enlarged as toward the apex (but not club-like as in P. breviceps). Frontal carina short, frontal area triangular, weakly defined. Ocelli small. Clypeus twice as wide as long or more, subcarinate, anterior border broadly emarginate medially. Mandible falcate, flattened and with minute serrations along inner border. Alitrunk with distinct promesonotal suture; metanotal groove strongly impressed. Propodeum bluntly rounded where declivity meets base. Petiole erect, thickened anteroposteriorly, more convex anteriorly than posteriorly, superior border blunt and subtruncate. Mandibles, clypeus, occipital lobes, underside of head, pronotum, prosternum, coxae, trochanters, flexor surfaces of legs, petiole and gaster with erect hairs. Pubescence on body fine, appressed, and sparse, but denser on appendages. (Identification from Smith, 1947).

This species can be separated from P. montivagus by its infuscation at the apex of gaster and erect hairs on the occipital lobes, both of which are lacking in P. montivagus. It can be distinguished from P. longicornis by its shorter antennal scapes, which are less than 1.2 times as long as the interocular distance in P. lucidus, but more than 1.4 times as long in P. longicornis; in P. lucidus, the head and alitrunk are shining, whereas, in P. longicornis, the body is opaque. Polyergus longicornis differs from P. breviceps by having much longer scapes, scapes in P. breviceps are not as long as interocular distance; by not having the antennal scapes terminating in a club (scapes in P. breviceps enlarged distally forming a club); and by having sparse pubescence on the gaster, whereas, pubescence on gaster of P. breviceps is dense).

Biology and Economic Importance
As with other Polyergus species, P. longicornis are obligate slave-makers.

This species has been reported from Arkansas, Florida, Georgia, Louisiana, and South Carolina (Dash, 2005; General and Thompson, 2007; Ipser et al., 2004; King and Trager, 2007; Smith, 1934; Smith, 1979).

Literature Cited
Dash, S. T. 2005. Species Diversity and Biogeography of Ants (Hymenoptera: Formicidae) in Louisiana, with Notes on their Ecology. M.S. Thesis, Louisiana State University, 290 pp.

General, D. M. and L. C. Thompson. 2007. Ants (Hymenoptera: Formicidae) of Arkansas Post National Memorial. Journal of the Arkansas Academy of Science 61: 59-64.

Hedlund, K. S. 2007. The Ants: North America Catalog: Genus Polyergus. (accessed 6 June 2008).

Ipser, R. M., M. A. Brinkman, W. A. Gardner, and H. B. Peeler. 2004. A survey of the ground-dwelling ants (Hymenoptera: Formicidae) in Georgia. Florida Entomologist 87 (3): 253-260.

King, J. R. and J. C. Trager. 2007. Natural history of the slave making ant, Polyergus lucidus, sensu lato in northern Florida and its three Formica pallidefulva group hosts. 14 pp. Journal of Insect Science 7: 42, available online:

Smith, D. R. 1979.  In Catalog of Hymenoptera in America north of Mexico. Smithsonian Institution Press, Washington D. C.  Vol. 2, pp. 1323-1427. 

Smith, M. R. 1934. A list of the ants of South Carolina. The Journal of the New York Entomological Society 42: 353-361.

Smith, M. R. 1947. A Study of Polyergus in the United States, based on the workers (Hymenoptera: Formicidae). The American Midland Naturalist 38: 150-161.


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