Comma Butterfly - Polygonia c-album

Comma butterfly

Taxonomy

Phylum: Arthropoda

Class: Insecta

Order: Lepidoptera

Family: Nymphalidae

Subfamily: Nymphalinae

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 butterfly with wings closed

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.

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.

Left: a Comma butterfly at rest. Picture courtesy of Simon Harding.

Comma butterfly on bracken

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.

Caterpillars of the Comma butterfly grow to a length of 3.5cm; they are dark brown and covered with branched spines some of which are black and others orange or white. The caterpillars can take up to five weeks to grow to maturity, at which point they 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.

Studying butterflies and moths...