Closely resembles Papilio chaon, from which it differs as follows: smaller; fore wing more produced, its termen concave. Male has the ground colour of the upperside of the wings a more brownish sooty-black. Hind wing with the upper discal white patch extended into interspace 4, most usually very slightly so, often represented only by a very small spot of white scaling, a white spot also above the tornal angle. Underside, fore wing: the internervular brownish-yellow streaks limited to the apical area of the wing. Hind wing: the upper discal patch extended to the dorsum in a series of three pure white not ochraceous-tinted spots, a more or less incomplete postdiscal series of lunules formed of diffuse blue scales, and the subterminal series of ochraceous lunules of a darker colour and smaller than in chaon; the rest as in chaon.
The upperside of the wing in females has the ground-colour paler than in chaon. Fore wing with an ill-defined broad pale discal band perceptibly widened and becoming whitish opposite apex of cell. Hind wing: the extension into interspace 4 of the upper discal white patch more pronounced than in the male, the small white spot above the tornal angle followed in some specimens by a blue ill-defined lunule and an ochraceous spot. Underside, fore wing: the transverse discal hand white and much more prominent than on the upperside. Hind wing: the postdiscal series of blue lunules generally complete and well-marked : the rest as in the male.
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Blue Helen
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