Comma Butterfly

Dead-leaf disguise

The comma’s wing outline is unlike any other British butterfly — deeply scalloped and jagged, mimicking a torn or decaying leaf. The underside is a mottled dark brown, and when the wings are closed the butterfly is almost indistinguishable from a dead leaf or piece of bark. This camouflage is used for winter hibernation, when the butterfly roosts among dead leaves or in dense ivy. The small white comma mark on the hindwing underside — the species’ namesake — is the only feature that distinguishes it at rest.

Two forms of the summer brood

The comma has a peculiar polymorphism in its summer generation. Larvae that develop early produce adults that breed again in summer (the hutchinsoni form, which is paler and more orange). Larvae that develop later produce a darker generation that overwinters as adults. The larvae cannot predict which strategy is appropriate based on their own condition alone; instead, the timing of their hatching relative to day length triggers the developmental switch.

A conservation success

The comma underwent a dramatic decline in the early 20th century, becoming confined to the Welsh Marches and a few English counties. By the late 20th century it had recovered and expanded — now one of Britain’s most common woodland-edge butterflies and a regular garden visitor. The reasons for both the decline and recovery are not fully understood, though changes in hop-growing (a larval foodplant) and climate may both have played a role. Recent range expansion northward into Scotland is likely linked to warming temperatures.

Autumn behaviour

In late summer and autumn, commas are among the most visible butterflies, feeding on windfall fruit and late-flowering ivy to build fat reserves before hibernation. They are particularly associated with gardens at this time, visiting fallen apples, pears, and plums.