Large tortoiseshell

Nymphalis polychloros
Upperside
Underside
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Family: Nymphalidae
Genus: Nymphalis
Species: N. polychloros
Binomial name
Nymphalis polychloros
Synonyms[1]

The large tortoiseshell or blackleg tortoiseshell (Nymphalis polychloros) is a butterfly of the family Nymphalidae.[2]

Subspecies

Subspecies include:[1]

  • Nymphalis polychloros polychloros
  • Nymphalis polychloros erythromelas (Austaut, 1885) – Algeria and Morocco

Distribution and habitat

This species can be found in most of Europe, northern Africa, and western Asia.[1][3] It is an extreme rarity in Britain, although it used to be widespread throughout England and Wales. Most of the specimens seen in Britain are thought to be captive-bred releases. These butterflies mainly inhabit woodland, especially with sallows (willows).[4]

Description

Nymphalis polychloros has a wingspan of 68–72 millimetres (2.7–2.8 in) in males, of 72–75 millimetres (2.8–3.0 in) in females.[4] These medium to large butterflies have orange to red wings with black and yellow spots and a dark brown edge. The dark border of the hind wings is decorated with dark blue lunulae. The underside of the wings is greyish brown. There is no sexual dimorphism.

This species looks very similar to the small tortoiseshell (Aglais urticae), but it is more closely related to the Camberwell beauty.

Biology

Caterpillar

The adult insect (imago) over-winters in dry dark places, such as hollow trees or out buildings. In late February or early March the butterflies emerge and mate. The females lay their pale green eggs (ova) in a continuous band around the upper twigs of elm (Ulmus spp.), sallow (Salix caprea and Salix viminalis), pear (Pyrus spp.), Malus, Sorbus, Crataegus, Populus, and Prunus spp. trees.[1][5]

The caterpillars (larvae) are gregarious, and systematically strip the topmost twigs of the tree bare. They seem to have little defence against predation by birds. It is possible that their decline and extinction in the British Isles (late 1970s) was owing to the loss of predatory birds, which previously had preyed upon smaller birds if they strayed to the tops of these trees.

The full-grown larva spins a silk girdle around a twig further down the tree, and hangs from this by means of hooks (cremaster) at its rear end, to pupate. The chrysalis (pupa) is greyish brown with a slight silvery sheen. The species is univoltine, i.e. there is only one generation per year,[4] the imagines emerging in July and August seek out sources high in sugar on which to feed. Tree sap and fermenting fruit are particularly popular.

References

  1. 1 2 3 4 Nymphalis polychloros at Markku Savela's Lepidoptera and Some Other Life Forms
  2. ↑ BioLib.cz
  3. ↑ Fauna europaea
  4. 1 2 3 UK Butterflies
  5. ↑ Paolo Mazzei, Daniel Morel, Raniero Panfili Moths and Butterflies of Europe and North Africa
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