sanctuaryofwings
Woodland brown (Lopinga achine), a species in the family Nymphalidae.
Photo: Didier Descouens · Wikimedia Commons · CC BY-SA

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Contents
  1. Identification
  2. Range and habitat
  3. Life cycle and host plants
  4. Behaviour and flight period
  5. Conservation
  6. Similar species

The woodland brown, Lopinga achine, is a grey-brown butterfly of the family Nymphalidae, named for its attachment to shaded forest. The species ranges across Europe, where it is local and declining in the west but more widespread further east, and continues through Russia and the Altai Mountains to China and Japan. Its caterpillars feed on grasses rather than the broadleaf plants many other butterflies use.

Identification

The woodland brown is a medium-sized satyrine with a wingspan of 45–55 mm. Both wing surfaces are grey-brown, marked with round dark eyespots of varying sizes set in yellow rims on the outer part of the wing. The underside carries an additional pattern near the outer edge, yellow lines with a black line running between them. Unlike many butterflies, the sexes are difficult to tell apart, showing little sexual dimorphism.

Range and habitat

This is a forest specialist. The butterfly favours damp, unmanaged mature forest with lush undergrowth, including shaded forest edges, clearings and river banks, with meadows near groves and larch or birch slopes used in Siberia. Across much of its continental European range it is widespread but uncommon and local, and it has already disappeared from several western countries. In the Carpathians it stays below about 400 m elevation, consistent with its preference for lowland, shaded woodland rather than open mountain slopes.

Life cycle and host plants

Caterpillars eat a range of grasses, including species of Elymus, Poa, Agropyron, Calamagrostis, Deschampsia, Brachypodium, Melica, Lolium and Triticum. Rather than fixing an egg carefully to a leaf, the female drops her eggs individually onto grass while flying over it. The resulting caterpillar is green with three dark lines along its back and a double light stripe along each side. It overwinters as a caterpillar, from around August until May or June, when it completes its growth and pupates.

The species manages one generation a year.

Behaviour and flight period

Adults are on the wing for a single, fairly short window: from late May to late July, occasionally running into August, across the European part of the range. The woodland brown keeps to the shade it is named for. Rather than visiting flowers for nectar, it mostly rests on tree trunks and vertical branches, and rarely comes to flowers at all. Males are the more visible sex, occasionally gathering on damp soil near water or on droppings, while females are more secretive and tend to fly high up in the tree canopy.

Conservation

The woodland brown is Vulnerable, the category shown in the facts box and recorded on its Wikidata item. Its retreat is concentrated in the west: the species has already been lost from parts of western Europe, even as it remains widespread further east, a pattern consistent with the loss of the damp, unmanaged, mature forest it depends on. Where it survives in central Europe it receives legal protection, for instance in Poland and Slovakia.

Similar species

  • Speckled wood (Pararge aegeria): another shade-loving woodland butterfly, but patterned with pale cream or orange spots on a dark brown ground rather than the woodland brown’s ringed eyespots.
  • Large wall brown (Lasiommata maera): shares a brown, eyespot-marked wing pattern, but favours open, sunlit rocky ground and woodland margins rather than the deep forest shade the woodland brown prefers.

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