|Typical individual, Kerala|
Not evaluated (IUCN 2.3)
The upper side of the rustic is ochraceous light brown. Its fore-wing displays some loop-like, slender, dark cellular markings with a broad, somewhat curved, transverse yellow discal band from costa to vein 1. The band does not reach the termen but broadens posteriorly.
The margins of the fore-wing are irregularly sinuous, with the inner defined broadly with black, and produced outwards in interspaces 3 and 4. Below this, the margin is squarely indented inwards in interspace 2 and outwardly convex in interspace 1. There is a curved series of three black spots. The and the largest is in interspaces 1, 2 and 3. The apical area beyond the band is black, with a conspicuous yellow subapical spot in interspace 5, and a paler ill-defined similar spot above it in interspace 6. In the posterior, the black area is produced narrowly to the tornus and encircles a yellow spot near the apex of interspace 2.
The hind wing features a transverse sinuous and very slender black line. This line is followed by a slender and somewhat lunular line; a transverse discal series of five black spots in interspaces 2 to 6; a postdiscal medially disjointed series or broad black lunules; a subterminal series of similar but straighter lunges; and a narrow terminal black band. The outer subbasal transverse line broadens at the costa, and is outwardly margined by pale spots in the interspaces. These are anteriorly white and well defined, and posteriorly obscure or often absent.
The underside of the wing is much paler. The discal band on the fore wing is pale, and the black lunules on the apical area are replaced by pale brownish ochre. There are some obscure markings in the cells of both the fore and hind wings.
Markings on the forewing include a discal, transverse, slender, chestnut-brown lunular line, bent inwards above vein 5, and bordered outwardly by a series of dark spots. The large black spot in interspace 1 is the same as that on the upper side. There are inner and outer transverse subterminal series of small dentate spots.
On the hindwing are indistinct cellular markings. The outer sub-basal dark transverse line is similar to that on the upper side, but is more clearly defined and very sinuous. There is a transverse discal series of uneven lunules, paler than the ground color, followed by a series of dark spots. There is a postdiscal very obscure pale lunular band, and a subterminal series of dentate dark spots, often obscure or obsolescent.
The antennae, head, thorax and abdomen are ochraceous brown. Beneath, the palpi, thorax and abdomen are a very pale ochraceous white.
The caterpillar is brown, with a dorsal and lateral series of darker brown markings. The head has two slender branched spines. Succeeding segments on either side feature a lateral series of semitransparent similar brown spines.
Subspecies and variants
- C. e. lotis is synonymised with the nominated subspecies. It's wingspan ranges from 45 to 55 mm.
- Var. nicobarica Felder generally, but not always, has the interspace between the postdiscal and sub-terminal transverse series of lunules on the upperside of the hind wing paler than the ground-color of the wings.
- Subspecies andamanica Moore has the upperside ground-colour a very dark ochraceous brown, much darker than in erymanthis. Markings on the upper and under side are similar, but on the upper side the spots on the discal band on the forewing are larger, especially the lowest spot. On the hindwing the upper three spots of the discal series are conspicuously larger. On the underside the ground colour is darker and the markings are more clearly defined than in the typical form.
- Subspecies placida, of southern India was previously considered a full species. The upper side differs as the forewing discal band is distinctly darker yellow. Its inner and outer margins are much less sinuous and irregular and the black line defining the inner margin is more slender. The spots on the band in interspaces 1,2 and 3 are much smaller, especially the spot in interspace 1, which is no larger than the others and is diffuse and ill-defined. The subapical yellow spots on the black area are usually absent or, if present, are diffuse and indistinct. On the hindwing, the outer sub-basal line, with its outer border of pale spots, is generally more clearly defined than in erymanthis. Both fore and hind wings are shaded at the base with olivaceous brown. Markings on the underside are similar to those in erymanthis but are more heavily defined.
Subspecies in India
- Cupha erymanthis maja, Fruhstorfer (1898), Sahyadri Rustic.
- Cupha erymanthis lotis, Sulzer (1776), Himalayan Rustic.
- Cupha erymanthis andamanica, Moore (1900), Andaman Rustic.
- Cupha erymanthis nicobarica, Felder (1862), Nicobar Rustic.
The Rustic caterpillars feed mainly on Flacourtiaceae species, for example Flacourtia montana, F. ramontchii, F. rukam, Xylosma racemosa and Scolopia species. They also eat plants such as Glochidion eriocarpum and Lepisanthes rubiginosum.
- Bingham, C. The Fauna of British India, Including Ceylon and Burma Lepidoptera 1905 (1).
- Davidson and Aitken Figure. Journal of the Bombay Natural History Society (1896) (10) p247.
- Robinson et al "HOSTS – a Database of the World's Lepidopteran Hostplants." NHM.ac.uk 2007. Accessed July 2007.
- Hamer, K. et al Diversity and ecology of carrion and fruit feeding butterflies in Bornean rain forest. Journal of Tropical Ecology 2006 (22) p25–33. DOI10.1017/S0266467405002750.