Butterflies of Thailand, Malaysia & Borneo
Orsotriaena medus  FABRICIUS, 1775
subfamily - SATYRINAE
subtribe - HYPOCYSTINA
Orsotriaena medus, Taman Negara, West Malaysia  Adrian Hoskins
Regrettably the popular name 'Nigger' was coined for this species in colonial times, and can cause unintended offence, but in the absence of an alternative we continue to use it here.
The genus Orsotriaena comprises of a single species medus. It bears a superficial resemblance to Mycalesis species but on the underside has only 2 ocelli on the forewing, and 3 on the hindwing. The upperside is dark brown and unmarked.
This is a very common and widespread species found from India and Sri Lanka to Thailand, and south through Malaysia to Sumatra, Borneo, Sulawesi, Timor, Papua New Guinea and northern & eastern Australia.
The Nigger is found in disturbed grassy habitats including forest glades, roadsides and riverbanks at altitudes between 0-250m.
The egg is shiny, spherical and straw-coloured. It is laid singly on blades and stems of grasses.
The caterpillar when fully grown is a dirty whitish colour, with a faint suffused dark stripe along the back. The body segments are vertically wrinkled, and covered with tiny tubercules. There is a pair of long pinkish caudal prongs projecting backwards from the anal segment. The head is pale brown and bestowed with a pair of long chestnut brown horns. The caterpillar feeds nocturnally on Oryza sativa, Saccharum officinarum and other grasses.
The chrysalis is yellow, stained with brownish, and has a long horn extending forward from the head. It looks rather like a tiny banana, and is attached by the cremaster to the underside of a grass blade, or to a nearby stem.
Adult behaviour
The butterflies are mainly active at dawn and dusk, or on overcast days, but can be seen also in sunny conditions.


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