Papilio polymnestor, the blue Mormon,[1][2] is a large swallowtail butterfly found in south India and Sri Lanka.

The forewing has a postdiscal band composed of internervular broad blue streaks gradually shortened and obsolescent anteriorly, not extended beyond interspace 6.

Hindwing with five irregular small patches of red at base, the outer three-fourths of the wing grey touched with ochraceous, but generally narrower than the blue on the upperside; the inner margin of the grey area crosses the wing beyond the cell; the postdiscal and subterminal black spots as on the upperside.

Mark Alexander Wynter-Blyth recorded it in Madhya Pradesh, Jharkhand, West Bengal, Sikkim and Kerala.

It is also common in deciduous forests and wooded urban areas, primarily due to the cultivation of its host plants, i.e. the Citrus species.

Periodically raids thicker forest patches, especially where Atalantia species are to be found in search of females to mate with.

Attracted to damp patch and has greater tolerance to other butterflies and humans while lapping up the mineral rich moisture.

[10] The eggs are laid singly on the upper surfaces of the leaves on rutaceous plants at ten feet or so above the ground.

[6] The caterpillar can be distinguished from the common Mormon, which it resembles, by its larger size, greenish head and a blue streak in the eyespot in segments 4 to 5.

[6] The pupa also resembles that of the common Mormon but is much larger and can be easily distinguished by the prominent folds on the lower side of the abdominal protrusion.