Large wall brown (Lasiommata maera): range, habitat and life cycle

The large wall brown, Lasiommata maera, is a butterfly of the family Nymphalidae found across much of temperate Eurasia. First described by Linnaeus in 1758, it ranges through continental Europe east through the Urals and southwestern Siberia to Asia Minor, Syria, Iran, Central Asia and the Himalayas, but is absent from the United Kingdom. Across this range eight subspecies are recognised, from the nominate form to populations in the Caucasus, Siberia, Armenia and the Atlas Mountains of Morocco and Algeria.

Identification

Wingspan runs from 44 to 56 mm. The species is quite variable in colour and pattern across its wide range, which is reflected in its many named subspecies; typically the upperside is orange on the forewings and mostly brown on the hindwings, with a single eyespot on each forewing and two or three on each hindwing. The underside is quieter: the forewing underside is orange, while the hindwing underside is marbled grey-brown, a camouflage pattern that suits a butterfly that rests on bark and stone. The sexes differ subtly in wing shape rather than colour: the male’s forewing is more pointed, with a longer costal margin and a more oblique outer margin than the female’s. It is similar to the smaller wall brown (Lasiommata megera), which has paler, yellow-orange forewings.

Range and habitat

Within its wide Eurasian range the species is common in continental Europe. It favours forest edges, unmanaged clearings in forested areas, rocky dry ground and stony slopes, from sea level up to 2,000 m, a spread of elevations that takes it from lowland woodland margins into montane grassland.

Life cycle and host plants

Caterpillars are grass feeders, recorded on Poa annua, Poa bulbosa, Poa pratensis, Festuca ovina, Festuca rubra, Festuca pratensis, Glyceria fluitans, Calamagrostis epigejos, Calamagrostis arundinacea, Calamagrostis varia, Deschampsia flexuosa, Agrostis capillaris, Nardus stricta, and species of Dactylis, Lolium and Hordeum. This broad list of grass genera matches a butterfly that breeds across open ground from lowland meadows to stony mountain slopes. The species produces two broods a year in the northern part of its range but only a single brood in the south, with adults on the wing from April to September.

Behaviour and flight period

Adults are strong, active fliers that are seldom seen on the wing in strong wind, a trait shared with other wall browns that bask and patrol over open, sunlit ground such as the rocky slopes and bare forest tracks that make up much of their habitat. Flight runs from April to September, with two broods in the north and a single brood further south.

Conservation

The species is assessed by the IUCN under the category shown in the facts box, taken from its Wikidata record. Its range runs from western Europe to the Himalayas and takes in eight recognised subspecies, spread across continental Europe, the Caucasus, Siberia, the Middle East and North Africa.

Similar species

• Wall brown (Lasiommata megera): the closest look-alike, smaller and paler, with yellow-orange rather than orange forewings.
• Speckled wood (Pararge aegeria): another woodland-edge member of the same subfamily, sharing its preference for dappled sun along forest margins.