Cardiocondyla obscurior is a small (~1.5 mm) nondescript, yellow to yellowish brown species with short antennal scapes and moderately sized propodeal spines, and without erect hairs on its mesosoma. The species is an accomplished tramp ant (Heinze et al., 2006)and has established populations across the world, including northern Europe (Rasplus et al., 2010; Seifert, 2003a), but it is not considered a pest or known to adversely affect native ecosystems. The restriction of the two non-tramp ants in the C. wroughtonii-group to India and Borneo suggest the native range of C. obscurior to be Southeast Asia. Cardiocondyla obscurior is polygynous, and often founds new colonies by nest splitting (Seifert, 2003a). Typical colony sizes are less than 500 workers (Seifert, 2003a). Unlike most of its congeners which nest in the soil, C. obscurior and its close relative C. wroughtonii nest in vegetation above the surface (Deyrup et al., 2000; Lupo & Galil, 1985). The reproductive strategies and caste determination of the species has been extensively studied, especially with respect to ergatoid males (Cremer et al., 2008; Heinze & Delabie, 2005; Heinze & Hölldobler, 1993; Kinomura & Yamauchi, 1987; Schrempf et al., 2007; Stuart et al., 1987).