MORPHOLOGY
External characteristics
Male
Forewings: There is a black coloured submarginal band. The upper side wing surface has a yellow ground-colour. The marginal band is black coloured and is clearly bordered and conspicuously concaved in each space (Yata and Morishita, 1979).
Female
Specimen from Kangean lack the orange subcostal patch on the forewing upper side, which is normally present in other specimen (D'Abrera, 1982).
Subspecies and variation
Two subspecies are described (D'Abrera, 1982; Yata and Morishita, 1979). There is a geographical variation in wing colouration of I. venilia, where the specimen from Kangean differs from specimen from Java in the faintly indicated black subapical band, which is located on the boundary between the orange and yellow area, is very heavy and broad (D'Abrera, 1982). There are three female forms known; the first one has on the upper side wing surface a yellow ground-colour and an orange subapical band; the second variety has a white ground-colour and an orange subapical band; the last one has both a white ground-colour as well as a white subapical band. Ssp. theresiae has reduced orange markings on the forewing upper side (Yata and Morishita, 1979).