Strumigenys smithii Forel 1886

Dacetini, Myrmicinae, Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia

worker face view

worker lateral view

Additional images: worker, dorsal view (small, large).


Belize and El Salvador south to Santa Catarina, Brazil, and Amazonian Bolivia; St. Vincent Island, Grenada Island. In Costa Rica: Atlantic and southern Pacific lowlands.


Apical fork of mandible with a single intercalary tooth; mandible with two conspicuous preapical teeth; gastral dorsum smooth and shining; mandibles shorter than head; propodeal lamellae with dorsal and ventral teeth or angles (dorsal angle absent in biolleyi). Also see Bolton (2000:539).

Head length 0.67-0.76mm, mandible length 0.36-0.42, CI 80-87, MI 52-61 (n=26 workers from 6 localities; Brown 1962).

In Costa Rica, smithii has a conspicuous ring of basal costulae on the gaster, these being approximately 0.10mm long on the midline. biolleyi has these costulae essentially absent or very short, less than 0.05mm on the midline. This difference is true for specimens from 28 different collections of biolleyi and 4 different collections of smithii that I have examined.

Similar species: biolleyi, godmani

Natural History

Brown and Wilson (1959) summarize the genus as follows:

"Widespread in tropics and warm temperate areas. Primarily forest-dwelling; some species occur in grassland and arid scrub. ... Nests mostly in soil and rotting wood; a few species live in arboreal plant cavities in tropical rain forest. Foraging hypogaeic to epigaeic-arboreal. Food: most species are collembolan feeders; a few are polyphagous predators or occasionally feed on sugary substances..."

Members of the genus are all predaceous, with a kinetic mode of attack (Bolton 1999).

smithii occurs in wet forest habitats. In Costa Rica, it perhaps nests and forages in the low arboreal zone. The few collections are from that zone, and I have never observed it in Winkler samples.

Selected Records

La Selva: nest in thick dead snag, soft and rotten, extending from tree trunk.

La Selva: nocturnal foragers on low vegetation.

Braulio Carrillo National Park at 500m: prey of Neivamyrmex gibbatus.

Corcovado National Park (Sirena): nocturnal forager.

Literature Cited

Bolton, B. 1999. Ant genera of the tribe Dacetonini (Hymenoptera: Formicidae). J. Nat. Hist. 33:1639-1689.

Bolton, B. 2000. The ant tribe Dacetini, with a revision of the Strumigenys species of the Malagasy Region by Brian L. Fisher, and a revision of the Austral epopostrumiform genera by Steven O. Shattuck. Memoirs of the American Entomological Institute 65:1-1028.

Brown, W. L., Jr. 1962. The neotropical species of the ant genus Strumigenys Fr. Smith: Synopsis and keys to the species. Psyche 69:238-267.

Brown, W. L., Jr., Wilson, E. O. 1959. The evolution of the dacetine ants. Quart. Rev. Biol. 34:278-294.

Page author:

John T. Longino, The Evergreen State College, Olympia WA 98505

Date of this version: 30 September 2008.
Previous versions of this page: 22 April 1997
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