A synoptic review of the ants of California (Hymenoptera: Formicidae). Author Ward, P. S. text Zootaxa 2005 936 1 68 http://antbase.org/ants/publications/21008/21008.pdf journal article 21008 Genus Solenopsis Westwood Two groups of Solenopsis occur in California. “Fire ants” are relatively large, grounddwelling species, with generalized foraging habits, aggressive workers and a painful sting. They include the widespread native species, S. xyloni McCook , and the recently introduced S. invicta Buren (red imported fire ant). “Thief ants” are small to minute species, previously placed in the subgenus Diplorhoptrum . These ants are predominantly subterranean, and difficult to identify. Species identification: keys in Trager (1991) (fire ants), Wheeler and Wheeler (1986g) and Mackay and Mackay (2002). Additional references: Buren (1972), Creighton (1930b), Gorman et al. (1998), Jones et al. (1982a), Knight and Rust (1990), Korzukhin et al. (2001), Morrison (2002), Porter and Savignano (1990), Ross and Trager (1991), Taber (2000), Thompson (1989).