Phragmatobia Stephens is briefly reviewed and a diagnosis is provided. The South American species currently placed in Phragmatobia Stephens are revised to two new genera, Andesobia Schmidt and De Freina, gen. n., and Patagobia Schmidt and De Freina, gen. n. (subtribe Spilosomina). Both Andesobia and Patagobia exhibit adaptations to high altitude habitats, including micropterous females in Andesobia (Patagobia females are unknown) and diurnal flight of males. The adults, immature stages, and mating behaviour of Andesobia jelskii (Oberthür, 1881) are described. Males of A. jelskii enter the female cocoon to mate, and the micropterous, flightless females remain in the cocoon following oviposition where newly hatched larvae feed initially on the female’s body.Four species are included in Andesobia, A. jelskii comb. n. (= Paracles imitatrix Rothschild, 1922, syn. n.), A. flavata (Hampson, 1901), comb. n., A. boliviana (Gaede, 1923), comb. n. (=Turuptiana flavescens Rothschild, 1933, syn. n.), and A. sanguinea (Hampson, 1907), comb. n. Patagobia includes only P. thursbyi (Rothschild, 1910), comb. n., and P. thursbyi pluto Toulgoët is relegated to its synonymy. Patagobia shows affinities to Phaos Walker, 1855 of Australia, Metacrias Meyrick, 1886 of New Zealand, and Pseudophragmatobia Krüger, 2009 of South Africa, suggesting a common ancestry of circumantarctic origin. Phragmatobia karsholti Toulgoët, 1991 is transferred to Venedictoffia Toulgoët, comb. n., an unrelated genus that is removed from subtribe Arctiina and provisionally placed in the Phaegopterina. Phragmatobia oberthueri Rothschild, 1910, described from Tibet, is a synonym of Lachana alpherakii (Grum-Grzhimailo, 1891) [Erebidae: Lymantriinae], syn. n., comb. n.