Comma Butterfly (Polygonia c-album) – Wildlife of Japan

Introduction

The Comma Butterfly, known in Japan as Shiitateha, is a northern woodland species recognized by its sharply notched wings and the small white comma mark on the underside. It occurs from Hokkaido to Kyushu, but it is most common in Hokkaido and the cool montane forests of Honshu.

Appearance

This medium-sized butterfly has a wingspan of about 5–6 cm. The upperside shows bright orange with dark spots, and the wing margins are deeply scalloped. The underside displays a brown, leaf-like pattern with a clear white C-shaped mark on the hindwing. In addition, it differs from the Asian Comma (Polygonia c-aureum) by having deeper wing indentations and no bluish spots on the hindwing upperside.

Habitat & Distribution

The species prefers deciduous and mixed forests, forest edges, and streamside woodland. It is widespread in Hokkaido and more local in the uplands of Honshu. However, it remains uncommon in the warm lowlands of western Japan. Its distribution closely follows elm trees, the primary larval host plants.

Behavior

Adults often bask on sunlit trunks and forest paths. Males defend small territories along forest edges. When the wings close, the butterfly blends almost completely into its surroundings due to its dead-leaf camouflage. Adults also feed on tree sap, fermenting fruit, and a small amount of nectar.

Diet

Larvae mainly feed on elm trees (Ulmus spp.), and some Cannabaceae plants may be used locally. Adults take nutrients from tree sap, overripe fruit, and limited flower nectar. Consequently, they appear frequently around sap flows and fallen fruit in late summer.

Reproduction

The Comma Butterfly usually produces two generations per year in Japan. Females lay eggs singly on elm leaves, and the spiny larvae grow on the host plant. The chrysalis resembles dried plant material. Finally, the species overwinters as an adult and often appears very early in spring.

Conservation

The species is not nationally threatened, but some regions have reported local declines where elm-rich forests and satoyama landscapes have changed. Because these habitats support elm stands, conserving deciduous forests and streamside areas remains essential for stable populations.

Author’s Impression

This butterfly can be very difficult to distinguish from similar species, so if you encounter one, please take a photo. Reviewing the images later will help you identify it with confidence.