Scotch Argus

Erebia aethiops (e-ruh-BEE-uh EE-thee-ops)

Scotch-Argus- 5D32869 Arnside Aug 2012
Photo © IainLeach
 

Wingspan
Male: 44 - 48mm
Female: 46 - 52mm

Checklist Number
59.008

Family:NymphalidaeRafinesque, 1815
Subfamily:SatyrinaeBoisduval, 1833
Tribe:ErebiiniTutt, 1896
Genus:ErebiaDalman, 1816
Subgenus:  
Species:aethiops(Esper, 1777)
Subspecies:aethiops (Esper, 1777)
 caledonia Verity, 1911

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Introduction

Despite its name, the Scotch Argus is not only found in Scotland; it is also found at two sites in the north of England. A freshly-emerged Scotch Argus is a sight to behold, the dark brown velvety uppersides making the butterfly appear almost jet black from a distance. The butterfly is unmistakable when seen basking with its wings open, when orange bands containing distinctive spots are revealed. This butterfly lives in well-defined colonies that are often very large.

Like the Mountain Ringlet, the ability of this butterfly to survive cool temperatures means that it was probably one of the first species to recolonise the British Isles after the last ice age, over 10,000 years ago. The English colonies, Arnside Knott and Smardale Gill, are both found in Westmorland. Colonies are much more numerous in Scotland, where this butterfly can be found in most of northern, western and south-west Scotland. This butterfly is absent from the lowlands of central Scotland, many of the western isles (including the Outer Hebrides), Orkney and Shetland.

A colony at Grassington in Mid-west Yorkshire, famous for a particular race that had reduced orange markings, became extinct in 1923. According to Dennis (1977) "This colony which used to occupy parts of Grass Wood was last observed by Clutten in 1923. The orange markings on the upperside of the males were nearly obsolete; and this feature in the females was scarcely better developed than in ordinary males".

Erebia aethiops ssp. aethiopsHistoric Specimens

This species was first defined in Esper (1777) as shown here and as shown in this plate (type locality: Southern Germany).

The nominate subspecies is found in England and the north-east of Scotland.

Scotch-Argus- 5D35205 Arnside Aug 2012

Male
Photo © IainLeach

Scotch-Argus-Arneside Knott 30 July 2011 03C4023

Male Underside
Photo © IainLeach

Scotch Argus - female - Arnside Knott - 28-Jul-14

Female
Photo © Pete Eeles

Scotch-Argus- 5D33883 Arnside Aug 2012

Female Underside
Photo © IainLeach

Photo Album ...


Erebia aethiops ssp. caledonia

This subspecies was first defined in Verity (1911a) as shown here and as shown in this plate (type locality: Galashiels, Scotland).

This subspecies is found in western and south-west Scotland although its distribution with regard to the nominate subspecies is by no means clear cut. The distribution shown here is taken from Thomson (1980). This subspecies differs from the subspecies aethiops as follows:

  • 1. Invariably smaller size.
  • 2. Forewings narrower and more elongated, with sharper angles and a straighter wing edge.
  • 3. The reddish yellow band is narrower and never contains more than three small eye spots.
  • 4. The bands on the underside of the hindwings are frequently indistinct.
Scotch Argus - male - Glen Kinglas - 17-Aug-15-4

Male
Photo © Pete Eeles

Scotch Argus - male - Glasdrum Wood - 17-Aug-15-17

Male Underside
Photo © Pete Eeles

Scotch Argus - female - Glasdrum Wood - 17-Aug-15

Female
Photo © Pete Eeles

Scotch Argus - Isle of Mull 30-July-2013

Female Underside
Photo © Jack Harrison

Photo Album ...


Conservation Status

Despite experiencing a long-term decline in its distribution, this butterfly has increased at monitored sites and is not, therefore, currently a priority species for conservation efforts.

UK BAP StatusDistribution Trend (%)Population Trend (%)
Not Listed
Stable+3
Decrease-33

The table above shows the distribution and population trends of species regularly found in the British Isles. The distribution trend represents a comparison between data for the periods 1995-1999 and 2005-2009. The information provided is taken from the Butterfly Conservation report The State of the UK's Butterflies 2011. The UK BAP status is taken from the UK Biodiversity Action Plan (UK BAP) (2007 review).

Habitat

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

Distribution

 

Click here to see the distribution of this species or here to see the distribution of this species together with specific site information overlaid.

Life Cycle

The flight period is fairly short for a butterfly that can appear in significant numbers. Butterflies emerge at the end of July, peaking in early August, with a few individuals surviving into September. There is one generation each year.

Erebia aethiops ssp. aethiops

Erebia aethiops ssp. caledonia

The chart(s) above have been correlated with the phenology plot below, taken from the UK Butterfly Monitoring Scheme. The blue line gives average counts over the full data set from 1976 to date, and the red line gives the average for the last year.

Imago

The adults are often the first butterflies of the day to be seen at suitable sites, their dark brown wings presumably allowing them to warm up more quickly than other species. They fly only when the sun is shining, and tend to retreat among grasses as soon as clouds appear, their undersides closely resembling a dead leaf. They reappear as rapidly when the sun comes out again and it is fascinating to watch an apparently-barren grassland come to life with butterflies as the clouds move away. Both sexes feed from a variety of nectar sources.

Males adopt both perching and patrolling strategies when in search of a mate. Males will fly for long periods when patrolling, searching out any dark brown object that is a potential mate. Females are mated shortly after they emerge with no discernable courtship involved, and the pair remain coupled for a few hours.

When egg-laying, the female selects sites that are in full sunshine and that are sheltered. She will bask for a while before crawling down into the grass and laying a single egg either on the grass or on nearby vegetation or debris. Eggs tend to be laid on Purple Moor-grass in Scotland and Blue Moor-grass in the Lake District.

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

Erebia aethiops ssp. aethiopsHistoric Specimens

Arneside Knott   25.07.11

Photo © Tony Moore
26-Jul-2011

Scotch-Argus- 5D36785 Arnside Aug 2012

Photo © IainLeach

Scotch Argus - Mating Pair - Arnside Knott, Cumbria - 27th July 2012

Photo © Graham Beckwith

Scotch Argus - male - Arnside Knott - 28-Jul-14-16

Photo © Pete Eeles
28-Jul-2014

Scotch Argus - imago - Arnside Knott - 22-Jul-05 (4) [Alan Thornbury]

Photo © Alan Thornbury

Scotch Argus Male - Arnside Knott, Cumbria 28-July-10

Photo © Vince Massimo
28-Jul-2010

Scotch Argus Female - Smardale Gill, Cumbria - 1st August 2010

Photo © Graham Beckwith
01-Aug-2010

Scotch-Argus-Arneside Knott 30 July 2011 03C4023

Photo © IainLeach

Scotch Argus - Arnside Knott - 20.07.13

Photo © PhiliB
20-Jul-2013

Scotch-Argus- 5D35729 Arnside Aug 2012

Photo © IainLeach

Scotch Argus - female - Arnside Knott - 28-Jul-14-2

Photo © Pete Eeles
28-Jul-2014

Scotch Argus (male) Smardale Gill, Cumbria  23-JUL-09

Photo © Trev Sawyer

Scotch-Argus-Arneside Knott 30 July 2011 03C2836

Photo © IainLeach

Scotch Argus - Arnside Knott - 21.07.13

Photo © PhiliB
21-Jul-2013

Scotch Argus - imago - Arnside Knott - 09-Aug-07 (1168)

Photo © Pete Eeles
09-Aug-2007

Scotch Argus - imago - Arnside Knott - 22-Jul-05 [Alan Thornbury]

Photo © Alan Thornbury

Scotch-Argus- 5D33883 Arnside Aug 2012

Photo © IainLeach

Scotch Argus - male - Arnside Knott - 28-Jul-14-9

Photo © Pete Eeles
28-Jul-2014

Scotch Argus Female - Arnside Knott, Cumbria 29-July-10

Photo © Vince Massimo
29-Jul-2010

Scotch Argus male - Arnside Knott 5.08.2013

Photo © Neil Freeman
06-Aug-2013

Photo Album ...


Erebia aethiops ssp. caledonia

Scotch Argus - female - Glasdrum Wood - 17-Aug-15-3

Photo © Pete Eeles
17-Aug-2015

Scotch Argus - male - Glen Kinglas - 17-Aug-15

Photo © Pete Eeles
17-Aug-2015

Scotch Argus - male - Glasdrum Wood - 17-Aug-15-13

Photo © Pete Eeles
17-Aug-2015

Scotch Argus - male - Glasdrum Wood - 17-Aug-15-18

Photo © Pete Eeles
17-Aug-2015

Scotch Argus - male - Glasdrum Wood - 17-Aug-15-14

Photo © Pete Eeles
17-Aug-2015

Scotch Argus - male - Glasdrum Wood - 17-Aug-15-16

Photo © Pete Eeles
17-Aug-2015

Scotch Argus - female - Glen Kinglas - 17-Aug-15-8

Photo © Pete Eeles
17-Aug-2015

Scotch Argus - female - Glasdrum Wood - 17-Aug-15-4

Photo © Pete Eeles
17-Aug-2015

Scotch Argus - Isle of Mull 4-Aug-2013

Photo © Jack Harrison

Scotch Argus - male - Glasdrum Wood - 17-Aug-15-17

Photo © Pete Eeles
17-Aug-2015

Scotch Argus - Isle of Mull 4-Aug-2013 (3)

Photo © Jack Harrison

Scotch Argus - female - Glasdrum Wood - 17-Aug-15

Photo © Pete Eeles
17-Aug-2015

Scotch Argus - female - Glen Kinglas - 17-Aug-15-7

Photo © Pete Eeles
17-Aug-2015

Scotch Argus - female - Glen Kinglas - 17-Aug-15-6

Photo © Pete Eeles
17-Aug-2015

Scotch Argus - Isle of Mull 30-July-2013

Photo © Jack Harrison

Scotch Argus - imago - Ardnamurchan - Unknown date [Adrian Riley]

Photo © Adrian Riley

Scotch Argus - Isle of Mull 30-July-2013 (2)

Photo © Jack Harrison

Scotch Argus ssp. caledonia - male - Glasdrum Wood, Scotland - 17-Jul-14

Photo © Pete Eeles
17-Jul-2014

Scotch Argus - male - Glasdrum Wood - 17-Aug-15-12

Photo © Pete Eeles
17-Aug-2015

Scotch Argus - male - Glasdrum Wood - 17-Aug-15-11

Photo © Pete Eeles
17-Aug-2015

Photo Album ...


Ovum

The spherical eggs are yellow when first laid, but turn light brown after a few days. This stage lasts between 2 and 3 weeks.

Scotch Argus - ovum - Unknown location - Unknown date (2) [REARED] [Reg Fry]

Photo © Reg Fry

Scotch Argus - ovum - Unknown location - Unknown date [REARED] [Reg Fry]

Photo © Reg Fry

Scotch Argus - ovum - Vaud, Switzerland - 31-Jul-06 [Guy Padfield]

Photo © Guy Padfield

Scotch Argus - ovum - Arnside Knott - 05-Aug-14

Photo © Pete Eeles
05-Aug-2014

Scotch Argus - ovum - Arnside Knott - 29-Jul-14

Photo © Pete Eeles
29-Jul-2014

Scotch Argus - ovum - Arnside Knott - 30-Jul-14-3

Photo © Pete Eeles
30-Jul-2014

Scotch Argus - ovum - Arnside Knott - 30-Jul-14-4

Photo © Pete Eeles
30-Jul-2014

Scotch Argus - ovum - Arnside Knott - 30-Jul-14

Photo © Pete Eeles
30-Jul-2014

Photo Album ...


Larva

When emerging from the egg, the larva nibbles around the top of the egg, but leaves a hinge, essentially creating a lid that it then opens. The eggshell is then partly eaten. Larvae feed during both day and night, but development is slow. Larvae hibernate while in the 2nd instar in leaf litter at the base of the foodplant. They emerge in the spring and mature larvae feed only at night, resting in ground debris during the day. There are 3 moults in total.

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

Scotch Argus - larva - Thatcham - 01-May-05 [REARED]

Photo © Pete Eeles
03-May-2005

Scotch Argus - larva - Thatcham - 16-May-05 (2) [REARED]

Photo © Pete Eeles
17-May-2005

Scotch Argus - larva - Thatcham - 16-May-05 [REARED]

Photo © Pete Eeles
17-May-2005

Scotch Argus - larva - Unknown location - Unknown date (4) [REARED] [Reg Fry]

Photo © Reg Fry

Scotch Argus - larva - Unknown location - Unknown date [REARED] [Reg Fry]

Photo © Reg Fry

Scotch Argus - larva - Thatcham - 23-Apr-14 [REARED]

Photo © Pete Eeles
23-Apr-2014

Scotch Argus - larva (1st instar) - Thatcham - 10-Aug-14 [REARED]

Photo © Pete Eeles
10-Aug-2014

Scotch Argus - larva - Glen Kinglas - 11-Jun-15

Photo © Pete Eeles
11-Jun-2015

Photo Album ...


Pupa

The pupa is formed in a loose cocoon, typically in mosses or some other soft material. This stage lasts between 2 and 3 weeks.

Scotch Argus - pupa - Thatcham - 13-Aug-12 (1) [REARED]

Photo © Pete Eeles

Photo Album ...


Aberrations

Description to be completed.

Click here to see the aberration descriptions and images for this species.

Similar Species

Mountain Ringlet

Description to be completed.

Videos


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The following links provide additional information on this butterfly.

References

The species description provided here references the following publications:

ReferenceDetails
Boisduval (1833) Boisduval, J.A. (1833) Icones historiques des Lépidoptères d'Europe nouveaux.
Dalman (1816) Dalman, J.W. (1816) Kongl. Svenska Vetenskaps akademiens Handlingar.
Dennis (1977) Dennis, R.L.H. (1977) The British Butterflies - Their Origin and Establishment.
Esper (1777) Esper, E.J.C (1777) Die Schmetterlinge in Abbildungen nach der Natur mit Beschreibungen.
Rafinesque (1815) Rafinesque, C.S. (1815) Analyse de la nature ou Tableau de l'univers et des corps organisés.
Thomson (1980) Thomson, G. (1980) The Butterflies of Scotland.
Tutt (1896b) Tutt, J.W. (1896) The Classification of British Butterflies. Entomologist's Record and Journal of Variation.
Verity (1911a) Verity, R. (1911) Races inédites de Satyridae européens [Lep. Rhopalocera]. Bulletin de la Société Entomologique de France.