Steven Cheshire's British Butterflies
British Butterflies: Species: Species Account - The Large Blue:
Large Blue
Glaucopsyche arion (Linnaeus, 1758)

Large Blue egg.
  Large Blue caterpillar.
  Large Blue chrysalis
Large Blue
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Insecta: Lepidoptera : Family Lycaenidae: Subfamily Lycaeninae : Genus Glaucopsyche: Species arion:
The Large Blue is as the names suggests is the largest of our Blue Butterflies and one of our rarest species. It is fully protected in Great Britain and as such must not be disturbed handled or interfered with in any way without a licence.

It is one of our most beautiful butterflies, despite its relatively small size compared to many of our butterflies. The deep blue upper wings and unmistakable arch of black spots and wing edges fringed with black on its upper forewing are unique among our butterflies.

The undersides of its wings are a silver-grey ground colour, becoming metallic silvery blue nearer to the body. Black spots cover the undersides which are fringed with white.

The British Race of the Large Blue became extinct back in 1979 due to habitat loss and poor management due to a lack of understanding of the butterflies needs. It has been re-introduced, albeit using a closely related species from the island of Öland, Sweden.

The first successful re-introduction occurred in 1983. During 1986, young larvae were imported to bolster the new population. Since then, the re-introduction programme has been a great success with many more sites now supporting this species.

The Large Blue is one of the most enigmatic of our British species. Its extinction was widely publicised in the early 1980's. The discovery of its remarkable life-cycle which involves spending the majority of its life-cycle as a larvae and pupae within the nests of red ants, where the larvae feed on the ant grubs was discovered between 1915-18 by Frohawk and Purefoy. However, it was not until the work of Jeremy Thomas in the late 1970's and the key discovery of the Large Blue's dependence on a particular species of Red Ant (Myrmica sabuleti) which itself requires specific environmental conditions in order to survive (i.e. warm, well drained grassland with very short sward and the presence of Wild Thyme) that the true reason for its extinction was known. It was the absence of the Red Ant from many of the former sites which ultimately lead to the loss of the Large Blue in the UK.

The Large Blue is a Priority Species for conservation due to the continued conservation work required to re-establish viable, self-sustaining populations.
The Large Blue requires warm dry unimproved acidic or limestone grassland where the larval food plant occurs. The sites must also contain healthy populations of a certain species of red ant namely Myrmica sabuleti.

The Large Blue is most active on warm sunny days but they do tend to rest and seek out warm pockets of grassland surrounded by vegetation during the middle part of the day. For the best views early morning or early evening is the best time to see the Large Blue, especially on days of broken cloud when individuals can be seen basking with their wings open wide to absorb heat from the sun.
The Large Blue is declining throughout Europe at an alarming rate and became extinct in Britain in 1979. The re-establishment of the Large Blue in Britain has resulted in the species now being present on 11 main sites where it is estimated some 10,000 adult butterflies flew in 2006 which is more than at any time in the last 60 years.
Where to see the Large Blue in the British Isles
NOTE: The following list of sites has been sourced from information already in the public domain. Some of the sites listed below are private. Permission must be sought before visiting these non-public sites.

Collard Hill (National Trust) is the only open public access site in the UK. All other sites are either accessible by prior arrangement or are closed to the public during the main flight season of the Large Blue.

20 breeding sites in the Polden Hills in Somerset include Collard Hill, Site X (famous as being the last site which the Large Blue occupied before becoming extinct in the UK), Green Down, Black Down and Gilling Down. The Large Blue has also been re-introduced to two other sites in the Mendips (Devil's Punchbowl and Hindhead Common).

In Cornwall, the Large Blue has been re-introduced to at least three locations on the north coast including a site south of Tintagel, coastal valleys north and south of Morwenstow and a National Trust owned valley called Dannonchapel, south of the village of Treligga where 12 adult butterflies and 300 larvae from Collard Hill were introduced in 2000.

In Gloucestershire, the Large Blue has been re-introduced to Daneway Banks near Sapperton.
Other notes
The following areas in the UK currenty have Biodiversity Action Plans which specifically targets threatend species such as the Large Blue as a response to the Rio Earth Summit in 1992. Cornwall.
Lifecycle chart
Flight chart
The lifecycle and flight charts should be regarded as approximate guides to the Large Blue in Britain. Specific lifecycle states, adult emergence and peak flight times vary from year to year due to variations in weather conditions.
IUCN category status 2010 5   IUCN category status 2007 34
Critically Endangered Critically Endangered

5Fox, R., Warren, M., Brereton, T. M., Roy, D. B. & Robinson, A.
(2010) A new Red List of British Butterflies. Insect Conservation and Diversity.
Critically Endangered Critically Endangered

3Fox, R., Warren, M & Brereton, T.
(2007) New Red List of British Butterflies. Butterfly Conservation, Wareham.

4More information about IUCN categories.
UK status
Larval foodplants
Wild Thyme (Thymus polytrichus) is the only food plant upon which the Large Blue will lay its eggs and the larvae feed. Eggs may be laid on Wild Marjoram (Origanum vulgare) but this rarely occurs in the UK as Marjoram tends to flower later here.

Upon reaching their fourth instar the Large Blue larvae drop from the food plant to be found by red ants which mistake the Large Blue larvae to be their own and they are taken back to the ants nest.

Once within the ants nest the Large Blue larvae will feed on the ant grubs. It is important to note that only with certain specific species of does this occur, namely (Myrmica sabuleti) and (Myrmica scabrinodis). However survival rates are much greater in larvae which feed within the nests of Myrmica sabuleti.
British subspecies
Glaucopsyche arion ssp. arion (Linnaeus, 1758)
Occurs in the UK. This subspecies was reintroduced to the British Isles. The stock originated from Sweden.
Glaucopsyche arion ssp. eutyphron (Fruhstorfer, 1915)
Occurred in the UK. This was the endemic species which is now extinct.
Butterflies of Britain ID Chart
Your personal guide to British Butterflies. This 8-panel laminated chart is designed for speedy butterfly identification in the field. Ideal for anyone interested in identifying butterflies, perfect for children and adults and ideal for outdoor use, laminated, shower-proof and robust. Get your copy today.
Butterflies of Britain (Laminated ID Chart).
Online store
Visit our online store for many more butterfly related books and gifts.
Population trends 1
UK Population trend 1995-2004 insuficient data
UK Population trend 1976-2004 insuficient data

1Fox, R., Asher. J., Brereton. T., Roy, D & Warren, M. (2006) The State of Butterflies in Britain & Ireland, Pices, Oxford.
UK BAP status 2
UK BAP status priority species (link)

2For information about the UK Biodiversity Action Plan, visit the JNCC web site

National Biodiversity Network Gateway
National Biodiversity Network Gateway Distribution Map

Areas in and indicate a contraction in distribution of the Large Blue except in Ireland where data is only available up until 1999.

* Records shown in outside the natural distribution may be the result of illegal or accidental releases by breeders or, depending upon the species, migrant individuals from mainland Europe.

Key to map*
= 2000 to 2010 inclusive (current distribution)
= records from 1950 to 1999 inclusive
= records from 1900 to 1949 inclusive
Records prior to 1st January 1900 are not shown.

The NBN Gateway records are shown on the map right. (See terms and conditions).

More data is available on the Large Blue on the NBN Gateway web site.
Powered by NBN Gateway.
For full details of books and reports mentioned on this web site, view the references page.

Find out more online*
Large Blue can be found on Peter Eeles excellent UK Butterflies web site.
Large Blue can be found on Matt Rowlings excellent European Butterflies web site.

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Photographs of the Large Blue
Image ID BB2199 - Large Blue - © Steven Cheshire
Large Blue female (imago)
BB2199 ©
Image ID BB2198 - Large Blue - © Steven Cheshire
Large Blue female (imago)
BB2198 ©
Image ID BB308 - Large Blue - © Steven Cheshire
Large Blue female (imago)
BB308 ©
Image ID BB307 - Large Blue - © Steven Cheshire
Large Blue female (imago)
BB307 ©
Image ID BB260 - Large Blue - © Steven Cheshire
Large Blue unknown (imago)
BB260 ©
Image ID BB105 - Large Blue - © Steven Cheshire
Large Blue female (imago)
BB105 ©
Image ID BB12 - Large Blue - © Steven Cheshire
Large Blue mating pair (imago)
BB12 ©
There are 7 photographs of the Large Blue in our stock photo library.
Aberrations and forms
There are 20 named aberrant forms of the Large Blue currently listed. Find out more about aberrants here.

ab. alconides - Aurivillius 1888
ab. caeruleomarginata - Tutt 1914
ab. conjuncta - Tutt 1914
ab. glomerata - Tutt 1914
ab. grisea - Courvoisier 1913
ab. imperialis - le Chamberlin 1908
ab. insubrica - Vorbrodt 1912
ab. magnifica - Heydemann 1910
ab. marginata - le Chamberlin 1908
ab. oolitica - le Chamberlin 1908
ab. pallida - le Chamberlin 1908
ab. parvipuncta - Courvoisier 1907
ab. postero-immaculata - Tutt 1914
ab. punctifera - Grund 908
ab. retrojuncta - Courvoisier 1911
ab. striata - Tutt 1914
ab. subtus-maculis-extensis - Oberthür 1896
ab. supra-impunctata - Oberthür 1896
ab. suprapuncta - Obraztsov 1936
ab. teleius - Bergstrasser 1779
Large Blue ab.insubrica