Eight, see text Polygonia c-album, or the “comma”, is a food generalist (polyphagous) butterfly species belonging to the family Nymphalidae.

Both the larval and adult stages exhibit protective camouflage, mimicking bird droppings and fallen leaves respectively, which reduces predation.

Although the species is not migratory, the butterflies are strong fliers, resulting in an open population structure with high gene flow and increased genetic variation.

The upper side of the wings has a bright orange color, decorated with brown marks and light spots on the edge.

The sexual dimorphism is slight and concerns the intensity of the coloration, the silhouette and the size, the male having a wingspan of 22 to 24 mm.

The seasonal dimorphism is more marked: the first generation ( hutchinsoni form, named for Emma Hutchinson,[2] May-June) has the upperside fawn orange and the underside brown-gold and the hindwing bears distally a broad dark red-brown area in which is situated a row of light brown hastate spots.

Within the genus Polygonia, a sister-group relationship between P. c-album and P. faunus is strongly supported by larval development analysis and synapomorphies.

Specifically, the species is commonly found in the woodland, country lanes, and garden areas of Norway, Sweden, and Great Britain.

[5][4] As a food generalist, or polyphagous species, comma butterflies can feed upon a variety of host plants, leading to widespread ranges across continents.

[10] The later instar larvae are specialized feeders and favor several host plants during the larval stage: Urtica dioica, Ulmus glabra, Salix caprea, R. uva-crispa, and Betula pubescens.

[9] Favoring plants in the family Urticaceae is speculated to have originated from the species' ancestors, providing an explanation for larval preference for U.

The mating success of both sexes is correlated to the duration of an individual's life, so no difference in mortality rates is observed between males and females.

[17] In theory, females would prefer host plants where their offspring performance is maximized, and the larvae would benefit from being able to feed on the best resources nearby their hatch site.

In P. c-album, instead of accepting the host plant that the female selected, first instar larvae leave their hatch site in search of alternative food sources.

[6] The eggs are green when first laid, and gradually turn yellow and ultimately grey before hatching,[19] which generally takes four to five days.

[23] Because of their wide distribution around the world, comma butterflies have a variety of vertebrate and invertebrate predators, including blue tits,[24] chickens,[7] and other birds.

The two main parasites that have been known to affect comma butterflies are Glypta erratica, a type of stem borer in Eupatorium, and Pteromalus vanessae.

In the fourth instar, the appearance of the larval body is relatively more colourful with white, black, and orange aposematic patterns.

A white stripe along its back mimics the pattern of bird droppings, further displaying protective colouration of the species.

Decreased predation by birds on P. c-album third-instar larvae has been shown compared to other larval stages, indicating that the spines increase defence.

The similarity is further exaggerated by the irregular wing edges, not resembling a typical butterfly, that are characteristic of the genus Polygonia.

[12] The diapausing morph is triggered when resources are allocated to survival, resulting in a less conspicuous, darker appearance of adults to avoid predation.

[4] Under cold winter conditions, adults can undergo diapause, a period of delayed sexual maturation to maximize survival.

The diapausing morph is more commonly observed in P. c-album butterflies inhabiting south Europe, North Africa, and Asia.

[10] Thus, their body temperatures do not elevate dramatically in the presence of sunshine, decreasing the effect that dark exteriors customarily have on biological processes such as metabolism and development rate.

In Britain, comma butterflies have shown the greatest shift in habitat and feeding resources, altering its preferred host plant from H. lupulus to U. glabra and U. dioica.

[28] In the 19th century, the British population of the comma crashed,[5][29] possibly as a result of reduced hop (H. lupulus) farming.

[30] Since the 1970s in Britain, specialist butterflies have decreased in population as their preferred habitat and host plants area becomes smaller.