Japanese Peacock Swallowtail (Papilio dehaanii) — identification, habitat & look-alikes

The Japanese peacock swallowtail is a large black swallowtail butterfly whose wings are dusted with metallic scales that shine blue-green depending on the angle. It lives in Japan and Korea and is not found in the wild in the United States. Summer adults are much bigger than the ones that emerge in spring.

Appearance

Appearance: Black wings sprinkled with shiny green scales, with tails on the hindwings and reddish eyespots along their edges. Males have a patch of black velvety hair on the forewings; females have larger, showier red spots.
Seasonal forms: Spring adults are noticeably smaller than summer adults.

Look-alikes

Alpine black swallowtailPapilio maackii

The alpine black swallowtail usually has a pale yellowish-white band on the underside of the hindwing, which this species lacks. A few individuals lose the band and are hard to tell apart.

Why they get mixed upBoth are big black swallowtails with blue-green metallic scales, and they share the same range in Japan and Korea.

Where it lives

Typical habitats: Forests
Wooded valleys
Rural edges
Range: Japan (Hokkaido to the Tokara Islands) and the Korean Peninsula. It is not native to North America.
Preferred conditions: Found where its citrus-family host trees grow; it can turn up in towns if host trees such as prickly ash are present.

Behavior

Activity: A fast flier. Males often gather on damp ground to sip water and also visit flowers.
Overwintering: Spends the winter as a pupa.

Life cycle

Caterpillar food plants: Caterpillars eat leaves of wild citrus-family plants such as prickly ash, cork tree (Phellodendron), and Japanese skimmia; in Japan they rarely use cultivated citrus.

Name and classification

About the name: It was long treated as part of the Chinese peacock swallowtail (Papilio bianor), but newer classifications treat the Japanese and Korean populations as a separate species, Papilio dehaanii.