Red helen swallowtail
Japan's largest butterfly hides a row of red crescent markings on the underside of its hindwings, invisible until it closes its wings.
| Where | Forests across southern Japan and Southeast Asia |
|---|---|
| Size | 110 to 140 mm wingspan |
| When | April to October |
This is a large, mostly black swallowtail with a broad white patch across the hindwing and red markings concentrated near the wing edges, more pronounced in females. It flies with slow, powerful wingbeats through shaded woodland.
Caterpillars develop on citrus relatives such as Japanese prickly ash, and adults visit flowers for nectar in forest clearings from lowland to mountain elevations. It occurs from southern Japan through much of continental Southeast Asia.
Traits
Habitat
Woodland
Colour
Black, White, Red
Active
Day
To people
Harmless to people; adults visit flowers for nectar and pose no threat when approached.
Activity through the year
Often confused with
Papilio nephelus has a larger, more yellow-tinted white patch on the hindwing without red spots near the tail, while Papilio helenus has a smaller white patch plus a full row of red crescent markings along the underside of the hindwing.
Questions
Is the Red helen swallowtail dangerous to people?
Harmless to people; adults visit flowers for nectar and pose no threat when approached.
When can you see the Red helen swallowtail?
The Red helen swallowtail can be seen from April to October, by day.
Plate retouched from a museum specimen photo by Kahanpää, Jere, Finnish Museum of Natural History - Zoology Unit, CC BY 4.0, GBIF Licence
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Butterflies and moths›Swallowtails›Papilio
Last updated 2026-09-27. Every entry is checked against published sources.