Scotch Argus (Erebia aethiops)
Species

Male. Taken at Arnside Knott, Cumbria, on July 30th 2014.
(1/60th sec at f13. Approx 2.5x lifesize. © David Hastings)

Male underside. Taken at Arnside Knott, Cumbria, on July 30th 2014.
(1/160th sec at f13. Approx 2.5x lifesize. © David Hastings)

Description

Wing span: 44 - 52mm

A freshly-emerged Scotch Argus is unmistakable, and appears almost jet black from a distance. When seen basking with its wings open, orange bands containing distinctive spots are revealed. This butterfly lives in well-defined colonies that are often very large.

It can be found in most of northern, western and south-west Scotland, and two sites in north-west England. It is widespread and locally common in southern and central Europe.

Most colonies are found in sheltered and damp areas such as woodland edges and riverbanks where the foodplant grows. The English colonies are situated in a different type of habitat, where sites are limestone grassland sheltered by woodland.

Butterflies emerge at the end of July, peaking in early August, with a few individuals surviving into September. There is one generation each year. The larva is the over-wintering stage.

The primary larval foodplants are Blue Moor-grass (Sesleria caerulea) and Purple Moor-grass (Molinia caerulea).

Adults feed primarily on Devil's-bit Scabious (Succisa pratensis), Field Scabious (Knautia arvensis), Heather (Calluna vulgaris), Knapweeds (Centaurea spp.), Marjoram (Origanum vulgare), Ragwort (Senecio jacobaea) and Thistles (Cirsium spp. and Carduus spp.).

Scotch Argus only fly when the sun is shining, and tend to retreat among grasses as soon as clouds appear. They reappear rapidly when the sun comes out again. Males will fly for long periods when patrolling, searching out any dark brown object that is a potential mate.

This species is of Least concern on the UK list.

Sightings

20-Jul-2018 : Vercors Natural Park, France
19-Jul-2018 : Vercors Natural Park, France
24-Jul-2015 : nr Kirilova polyana, Bulgaria
30-Jul-2014 : Arnside Knott, Cumbria (12+)
29-Jul-2014 : Smardale Gill NNR, Cumbria (25+)