Linepithema is a genus of ants native throughout the New World tropics and sub-tropics in a variety of forest, montane, and riparian habitats.  These ants show highly developed foraging behavior and are generalist predators, scavengers, and avid tenders of honeydew-secreting insects.  Worker Linepithema are small and monomorphic.  Colonies tend to be populous assemblages of several thousand individuals.  One species, the Argentine ant L. humile (Mayr 1868), has become an ecologically invasive cosmopolitan pest, particularly in Mediterranean climates in North America, Chile, South Africa, Australia, and southern Europe.

I have recently completed the first taxonomic revision of Linepithema, recognizing 19 species. The revision is open-access and can be downloaded here.  Forthcoming is a multi-locus molecular phylogeny.  The phylogeny identifies a sister taxon to the Argentine ant, estimates the ancestral region for the genus, and discusses the implications of multiple gene trees for species-level taxonomy.

For the purpose of facilitating identification, I have posted specimen images, including images of type material, at www.antweb.org.  Antweb also holds the complete database of distribution and collection information included in the revision.  I am currently working on an online identification key that will appear here shortly.

Linepithema dispertitum (Dominican Republic)

Linepithema piliferum (Ecuador)

Linepithema humile (Argentina)

Wild, A. L. 2007. Taxonomic revision of the ant genus Linepithema (Hymenoptera: Formicidae). University of California Publications in Entomology 126: 1-159.

Wild, A. L. 2004. Taxonomy and distribution of the Argentine ant Linepithema humile (Hymenoptera: Formicidae).  Annals of the Entomological Society of America 97(6): 1204–1215.