MORPHOLOGY

External characteristics

Male
Forewing length (mm): 70-75. Wingspan (mm): 114-116.
Forewings: Upperside whitish, may be a bit yellowish near wing base; outer margin and all veins dark brown, complete series of large rounded dark brown submarginal spots, a large spot across middle of cell and at end of cell, dark brown color along vein 3 may expand into an indistinct spot; underside similar Hindwings hardly crenulate, but appears so because narrow dark brown border is heavier at the end of the veins and the fringes between the veins are white, no tail; upperside whitish, all veins well marked in dark brown, complete series of well developed submarginal spots, also spot at end cell; underside similar.

Female
Forewing length (mm): 80. Wingspan (mm):127.
As male, but the dark brown colour is more expanded and pale yellow in the basal part of the wings more conspicuous.

Subspecies and variation

Slight individual variation in the expansion of the dark brown color, but no geographic variation reported.

Similar species

Remarkably similar to species of the genus Idaea (Nymphalidae: Danainae), hence the name. The latter are poisonous. Papilionidae can always be distinguished from Nymphalidae (and other butterflies, for that matter) by the possession of a single anal vein in the hindwing, instead of two.

_{source: Jan Moonen, peronal communication 2020}