Comma Butterfly - Polygonia c-album

Phylum: Arthropoda - Class: Insecta - Order: Lepidoptera - Family: Nymphalidae

The comma butterfly gets its name from a distinctive comma-shaped white mark on the underside of each hindwing (pictured below).

The ragged shape and dull brownish grey colouring of the underwings makes it look like a dead leaf when the wings are closed at rest (see picture below), and no doubt this is a valuable defence mechanism against predation by birds.

Comma butterflies have a wingspan ranging between 5 and 6cm.

Distribution

Now widely distributed across England and Wales but confined in Scotland to the border region, the Comma is a very rare sight in Ireland.

Above: Commas with a Red Admiral

Elsewhere, this butterfly is well represented in all but the most northerly countries of Mainland Europe. It occurs in parts of North Africa, and its range extends eastwards through Asia including Japan.

Lifecycle

There are two distinct generations of Commas. A summer generation emerges in June and July, followed by an autumn generation in August and September. The one shown above is an autumn emerger; the comma butterflies of summer are rather darker in colour. The autumn commas hibernate as adults and reappear in spring.

Stinging Nettle, (Urtica dioica) is the main larval foodplant of the Comma, but these butterflies are also known to use hops, elms and willows occasionally. The greenish ribbed eggs are generally laid on larval foodplants beside hedgerows, at woodland edges, or in woodland glades and rides. Depending on the weather it can take anywhere between two and three weeks for the eggs to hatch, during which time they turn yellowish and eventually grey.

Above: a first instar Comma larva

Caterpillars of the Comma butterfly grow to a length of 3.5cm; at maturity they are dark brown and covered with branched spines some of which are black and others orange or white.

Above: an early instar larva

The caterpillars can take up to five weeks to grow to maturity, at which point they pupate.

Above: a Comma larva about to pupate

The chrysalis is a jagged form, coloured green and brown so that, hanging from a nettle stem, it very much resembles a curled up dead leaf.

Etymology

The genus name Polygonia come from Greek, Poly meaning many and gonia meaning angles. It is a reference to the many-faceted wing shape of butterflies in this group. Carl Linnaeus gave this species its scientific name c-album, meaning 'White letter C" - a reference to the comma-like or C-shaped white marking (album means white) visible on the underwing.

Acknowledgements

This page includes pictures kindly contributed by Zoran Bozovic, Simon Harding, Betty and Tony Rackham, and James Wainscoat.

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