|Male, La Plata, Buenos Aires province, Argentina|
Danaus erippus, the southern monarch, is a milkweed butterfly (subfamily Danainae) in the family Nymphalidae. It is one of the best known butterflies in South America. Its genome is nearly identical to D. plexippus, but the two are incompatible, and therefore considered separate species.
Danaus erippus is included with other Nymphalidae, the largest family of butterflies with about 6000 species distributed throughout most of the world. It has a reduced pair of forelegs, is brightly coloured, and is included with popular species such as the emperors, admirals, tortoiseshells, and fritillaries. Its wingspan reaches about 110 millimetres (4.3 in), with an easily recognizable orange and black pattern. Until 2007, this butterfly was treated as a subspecies of Danaus plexippus. These species are very similar, but D. erippus usually has an orange trailing edge of the forewings, while in D. plexippus it is black. The lineages of the two species are thought to have separated about 2 million years ago. The colour of the wings in males of the southern monarch is paler than in the females.
Though, not as well known as the eastern North American monarch migratory phenomenon, it has been observed to move in a consistent spring/autumn manner by flying south in the autumn towards colder latitudes for the winter. Massive overwintering roosts have not yet been found.
Larval food plants
D. erippus differs from D. plexippus in that it utilizes host plants that are not in the genus Asclepias including: Astephanus geminiflorus, Cynanchum boerhaviifolium, Cynanchum atacamense, and Tweedia birostrata. There are only 12 Asclepias species in South America: A. barjoniifolia, A. boliviensis, A. mellodora, A. candida, A. "flava", and A. pilgeriana. Larvae do feed on the introduced A. curassavica.
- Hay-Roe, M.M., Lamas, G. & Nation, J.L. (2007). Pre- and postzygotic isolation and Haldane rule effects in reciprocal crosses of Danaus erippus and Danaus plexippus (Lepidoptera: Danainae), supported by differentiation of cuticular hydrocarbons, establish their status as separate species. Biological Journal of the Linnean Society 91:445–453.
- Brower, A.V.Z.; Jeansonne, M.M. (May 2004). "Geographical populations and "subspecies" of New World Monarch butterflies (Nymphalidae) share a recent origin and are not phylogenetically distinct". Annals of the Entomological Society of America. 97 (3): 519–523. doi:10.1603/0013-8746(2004)097[0519:GPASON]2.0.CO;2.
- Malcolm, S. (2012). "Presentation of a paper at the Monarch Biology and Conservation Meeting: Migration and host plant use of the southern monarch, Danaus erippus" (PDF). Minnesota: Monarchlab.org. Archived from the original (PDF) on June 25, 2013. Retrieved August 19, 2014.
- Hayward, K.J. (1962). Migration of butterflies and a moth in Argentina, spring and summer 1960-61. The Entomologist 95:8-12.
- Southern Monarch, Biolib
- "Danaus Kluk, 1780" at Markku Savela's Lepidoptera and Some Other Life Forms
- Dockx, Cristina (2002). Migration of the North American monarch Danaus plexippus to Cuba, PhD dissertation. University of Florida.