Steven Cheshire's British Butterflies
British Butterflies: Species: Species Account - The Silver-studded Blue:
Silver-studded Blue
Plebeius argus (Linnaeus, 1758)

Silver-studded Blue egg.
ova
  Silver-studded Blue caterpillar.
larva
  Silver-studded Blue chrysalis
pupa
Silver-studded Blue
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Nomenclature
Insecta: Lepidoptera : Family Lycaenidae: Subfamily Lycaeninae : Genus Plebeius: Species argus:
Description
The silver-studded Blue is a stunning little butterfly which sometimes occurs in large numbers within compact colonies. Individuals rarely fly any distance from their colony.
 
Males are usually seen basking or flying low over vegetation on the search for newly emerged females. There is one brood each year.

The female will lay her eggs singly on the larval foodplant or on other vegetation nearby. They prefer to lay their eggs close to the ground in sheltered spots where the slightly higher average tempereature (micoclimate) helps in the development of the young larva within the egg. The larva is fully developed within the egg but does not emerge until the following spring.

When the larva does emerge, it first feeds on the young tender shoots and buds of the foodplant. As the larvae grow they will feed on less tender leaves and are often attended by ants. It is thought that the ants provide some protection from predators and in return the larva exudes sweet secretions from a gland near its rear end. The larval stage occurs over 4 instars before pupation takes place in a silk lined chamber just below the ground surface where again it is often tended by ants.

Ants continue to attend even when the adult butterfly begins to emerge from the pupa.
Habitat
The Silver-studded Blue prefers lowland heathland or calcareous (limestone or chalk) grassland as its main habitat but also occurs on a peatland site in Wales.

As with the Large Blue the Silver-studded Blue has an important relationship with ants in this case with the genus Lasius which requires open ground (bare soil or short vegetation) which provide relatively warmer microclimates at ground level compared to the surrounding area. This requirement becomes increasingly important towards the northern limit of the species range where it prefers sheltered areas or those that are south-facing.

Sites where the habitat has been grazed following recent disturbance such as quarrying or heathland fires tend to hold the stongest populations with ideal conditions for breeding occuring after 4 years of regrowth of the larval foodplant.

Many sites are managed in a way to replicate these processes. Domestic animals may be used to graze the vegetation folowing mechanical cutting or controlled burning. If management is not sustained the habitat quickly becomes unsuitable often within 10 years. As a result most populations of the Silver-studded Blue exist as metapopulations. Occasional dispersals of adults allowing suitable habitat nearby to be colonised.

It is also important for the Silver-studded Blue to have areas of long grass and/or low shrubs which offers protection against stong winds as they tend to roost communally at night and during poor weather.
Distribution
During the last century it is thought that the Silver-studded Blue undergone a severe decline in its range by an estimated at 80%. It is extinct in Scotland and northern England and absent throughout the majority of central eastern and south-eastern England. It is widespread on the heaths of Dorset and Hampshire with strong populations occuring in North Wales.
Where to see the Silver-studded Blue in the British Isles
Cornwall: St Day nr Redruth
Dorset: Higher Hyde, Studland, Tadnoll, Portland Broadcroft Quarry, Portland Perryfields,
Portland Tout, Avon Heath CP North, Avon Heath CP South, Sopley Common
Merseyside: Thurstaston Common SSSI (introduced in 1994 - present on SE part of reserve)
Norfolk: Buxton Heath and Kelling Heath (re-introduced)
Shropshire: Prees Heath BC Reserve
Suffolk: RSPB Minsmere and Westleton Heath.

A new colony of Silver-studded Blues was discovered in 2006 on the RSPB’s Minsmere reserve. Over 3000 individuals were recorded following the conversion of the land from arable fields to grassland and heathland since the 1990's. Another good site is the English Nature managed site at Sunnyside Farm Stoborough Heath Ridge near Wareham.
Other notes
The following areas in the UK currenty have Biodiversity Action Plans which specifically targets threatend species such as the Silver-studded Blue as a response to the Rio Earth Summit in 1992. They can also be found at sites in Pembrokeshire Rhondda Cynon Taff Cornwall Cheshire Denbighshire Shropshire Suffolk and Teignbridge.
Lifecycle chart
ovaovaovalarvaelarvaelarvaelarvaepupapupaadultadultovaovaovaova
 
Flight chart
JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember
The lifecycle and flight charts should be regarded as approximate guides to the Silver-studded 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
Vulnerable Vulnerable

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

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

4More information about IUCN categories.
Wingspan
26-31mm
UK status
Resident
Larval foodplants
On acid heathland the larvae feed on Heather Crossed-leaved Heath Bell Heather and Gorse while on calcareous grassland Common Rockrose Common Birds-foot-trefoil and Horseshoe Vetch are used.
British subspecies
Plebeius argus ssp. argus (Linnaeus, 1758)
Occurs in southern and eastern England. It is the most widespread of the sub-species occuring throughout the species range.
Plebeius argus ssp. caernensis (Thompson, 1937)
Occurs in Limestone areas of north Wales only, centred on Great Ormes Head. Known as the Western Silver-studded Blue, this sub species is smaller than ssp. argus. The female also tends to have more blue colouration to the uppersides of her wings.
Plebeius argus ssp. cretaceus (Tutt, 1909)
Occurs in Dorset only - restricted to quarry sites on Portland Bill. Colonies also exisited in Kent, Surrey and Essex but these are now extinct. Known as the Southern Silver-studded Blue, this subspecies differs from the ssp. argus by its larger size and the reuced with of the dark margings to the upper wings. The male is also brighter blue in colour.
Plebeius argus ssp. masseyi (Tutt, 1909)
Occurs in Shropshire at the Butterfly Conservation Reserve at Prees Heath only - other colonies in Lancashire and Westmoreland are now extinct. Known as the Northern Silver-studded Blue, ssp. masseyi differs from ssp. argus by the much narrower dark border to the upper surfaces of the wings which reveal clear marginal spots on the rear wings of the males. The male undersides tend to be chalky grey in colour. Females tend to have a flush of blue colouration across much of the upper surface of the hind wings.
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).
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Population trends 1
UK Population trend 1995-2004 down by -72%
UK Population trend 1976-2004 down by -1%

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 jncc.defra.gov.uk.

National Biodiversity Network Gateway
National Biodiversity Network Gateway Distribution Map



Areas in and indicate a contraction in distribution of the Silver-studded 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 Silver-studded Blue on the NBN Gateway web site.
Powered by NBN Gateway.
References
For full details of books and reports mentioned on this web site, view the references page.

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

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Photographs of the Silver-studded Blue
Image ID BB2318 - Silver-studded Blue - © Debbie Cheshire
Silver-studded Blue male (imago)
BB2318 ©
Image ID BB2317 - Silver-studded Blue - © Debbie Cheshire
Silver-studded Blue male (imago)
BB2317 ©
Image ID BB2316 - Silver-studded Blue - © Debbie Cheshire
Silver-studded Blue male (imago)
BB2316 ©
Image ID BB2315 - Silver-studded Blue - © Debbie Cheshire
Silver-studded Blue female (imago)
BB2315 ©
Image ID BB2314 - Silver-studded Blue - © Debbie Cheshire
Silver-studded Blue female (imago)
BB2314 ©
Image ID BB2313 - Silver-studded Blue - © Debbie Cheshire
Silver-studded Blue male (imago)
BB2313 ©
Image ID BB2312 - Silver-studded Blue - © Debbie Cheshire
Silver-studded Blue male (imago)
BB2312 ©
Image ID BB2311 - Silver-studded Blue - © Debbie Cheshire
Silver-studded Blue male (imago)
BB2311 ©
Image ID BB2310 - Silver-studded Blue - © Debbie Cheshire
Silver-studded Blue female (imago)
BB2310 ©
Image ID BB2309 - Silver-studded Blue - © Debbie Cheshire
Silver-studded Blue female (imago)
BB2309 ©
There are 99 photographs of the Silver-studded Blue in our stock photo library.
View more photographs of the Silver-studded Blue as a thumbnail gallery or as a slideshow.
Aberrations and forms
There are 33 named aberrant forms of the Silver-studded Blue currently listed. Find out more about aberrants here.

ab. anterocroceus - Tutt 1909
ab. argyrotoxus - Bergstrasser 1779
ab. basijuncta - Tutt 1909
ab. bina - Rostagno 1906
ab. caeca - Grund 1908
ab. costajuncta - Tutt 1909
ab. croceolunulatus - Tutt 1909
ab. croceovirgatus - Tutt 1909
ab. cuneata - Tutt 1909
ab. disco-anteriora - Tutt 1909
ab. disco-lunulata - Tutt 1909
ab. flavescens - Tutt 1909
ab. fulvescens - Tutt 1909
ab. furvescens - Wykes 1945
ab. fuscescens - Lempke 1955
ab. infraobscura - Lempke 1955
ab. juncta - Tutt 1909
ab. leodorus - Gerhard 1853
ab. magnipuncta - Tutt 1909
ab. minor - Tutt 1909
ab. nigrescens - Tutt 1909
ab. obscura - Grund 1908
ab. pallida - Tutt 1909
ab. posterocroceus - Tutt 1909
ab. privata - Courvoisier 1910
ab. purpurascens - Tutt 1909
ab. radiata - Oberthür 1896
ab. rufescens - Tutt 1909
ab. transversa - Wykes 1945
ab. tribasijuncta - Courvoisier 1912
ab. ultranubila - Wykes 1945
ab. unipuncta - Mousley 1902
ab. violascens - Tutt 1909
Silver-studded Blue ab.cuneata