Butterflies of the World - Lifecycle, Ecology, Taxonomy, Conservation, Photography, Butterfly Holidays, Photo Galleries, Book Reviews and more.........
Text and photographs protected by Copyright © Adrian Hoskins 2007, and must not be published in part or in whole elsewhere without prior written permission from the author.
Butterflies of Britain & Europe
 
Scotch Argus
Erebia aethiops ESPER, 1777
Family - NYMPHALIDAE
subfamily - SATYRINAE
Tribe - SATYRINI
subtribe - EREBIINA
 
 introduction | habitats | lifecycle | adult behaviour
 
Erebia aethiops, male, Loch Garry, Scotland
 
Introduction
 
The Scotch Argus is distributed in central and eastern Europe, and it's range extends to northern Turkey and across temperate Asia to western Siberia. It is absent from Ireland, Spain, Portugal, western France, peninsular Italy, Scandinavia and the Mediterranean region.
 
The upperside is similar to that of several other Erebia species which occur in Europe, including ligea, euryale, medusa and triaria. The species can be distinguished from each other by examination of the arrangement of the ocelli, and by differences on the under-sides. A good field guide is essential for determination.
 
There are no similar species in Britain, although aethiops could be confused in flight with the Ringlet Aphantopus hyperantus. The Arran Brown Erebia ligea, which is very similar to aethiops but has prominent white markings on the underside hindwings, was allegedly found in Scotland in the 19th century, but all records are regarded as dubious.
 
Habitats
 
In Britain the Scotch Argus is confined almost exclusively to Scotland. In England it is known to have formerly occurred at several sites in Cumbria, Yorkshire, Northumberland and County Durham; and probably also in Lancashire, but is now only found only at 2 sites - Arnside Knott in Cumbria, and Smardale Gill in Yorkshire.
 
Unlike most members of the genus Erebia, the Scotch Argus is not a montane species. It occurs at elevations below 500m, primarily in damp situations where the grasses Molinea caerulea or Sesleria caerulea grow in tall, lush, dense tussocks.
 
In Scotland the butterfly is commonly found in valley bottoms, and at damp grassland / woodland mosaic habitats, particularly those along riverbanks, or around the edges of lochs. Colonies also occur on warmer, more sheltered areas of lightly wooded moorland, on scrubby damp heaths and hillsides on the islands of the Inner Hebrides, as well as on the mainland.
 
The 2 sites in northern England are different in nature - at Arnside Knott it occurs on limestone where rough grassland is sheltered by woodland; and at Smardale it is found along a disused railway line running through limestone woodland.
 
Lifecycle
 
The butterflies emerge in late July and throughout August.
 
They lay their eggs singly on grass blades and stems, at the base of tussocks of purple moor grass Molinea caerulea ( Scotland ) or blue moor grass Sesleria caerulea ( Cumbria, Yorkshire ). In continental Europe a wider range of grasses are used including Bromus, Brachypodium, Festuca, Poa, and Dactylis. At some sites in Europe they oviposit on the sedge Carex sempervirens.
 
The eggs are spherical, finely ridged, and straw coloured with darker speckles. They hatch after about 2 weeks, in late August.
 
The caterpillars only feed for a few weeks before entering into hibernation. They over-winter at the base of grass tussocks, awakening in late April to resume feeding. When fully grown they are a dull greyish green, with dark green stripes along the back and sides. They feed nocturnally.
 
The fully grown larva leaves the foodplant in mid June, and wanders a short distance to pupate in a small cavity excavated amongst mosses. The pupa is pale brown, with dull purplish thorax, wing cases and eye covers.
 
Adult behaviour

 

The butterfly forms large colonies often numbering dozens, hundreds or even thousands of individuals.

 

During overcast or cool weather they roost amongst tall grasses, or in bushes, and are only active in warm sunshine. In warmer conditions they commonly bask on bracken, on bushes, or amongst grasses, with wings held fully open.

 

The flight of males is gentle but persistent, fluttering amongst the tall grasses, dipping down at intervals in search of potential mates. Copulation takes place in late morning amongst grasses, and lasts for about an hour. Females are quiescent until mated, after which they can be seen flying in and out amongst grass tussocks to oviposit.

 

Both sexes nectar avidly at almost any available flowers including thistles, knapweeds, bramble, hawkweeds, heather and meadowsweet; fluttering from flower to flower, and usually holding the wings half-open while feeding.

 
                                                       
Almost every British and European species of butterfly is declining rapidly in numbers, due in most cases to loss or degradation of habitats.
 
You can help to reverse the decline by supporting conservation organisations which purchase and manage habitats as nature reserves, and which lobby government at local, national and international levels, often very successfully, to bring about changes in farming, forestry and urban development policies.
 
Please contact the conservation organisations for advice on how you can help protect British and European butterflies and their habitats. You may be able to offer practical help e.g. by monitoring butterfly populations or helping to manage nature reserves. Donations to these organisations enable them to employ ecologists and biologists. Even if you are unable to provide such help, merely having your name on the membership list can be a powerful tool for conservation organisations wishing to demonstrate the levels of support they have for their policies.

 

 
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