British Butterflies - An Online Guide by Steven Cheshire
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UK Status  
Resident A species which is continually Resident in the UK with stable breeding populations.
Migrant A species which occurs as a Migrant in the UK. It may be able to breed here although they are usually unable to survive our winter months. Migrants are normally reported in the UK every year.
Rare Migrant A species which occurs as a Rare Migrant in the UK. It may able to breed here although they are usually unable to survive our winter months. Rare Migrants may not be seen for many years.
Extinct A species which is Extinct in the UK, usually as a result of habitat loss.
Introduction A species which ocurs in the UK as an accidental introduction.
Chalkhill Blue Chalkhill Blue
Polyommatus coridon
(Poda, 1761)

Family: Lycaenidae
UK Status: Resident
wingspan33-40mm

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Nomenclature
Insecta (Insects): Lepidoptera (Butterflies & Moths): Lycaenidae (Family): Lycaeninae (Subfamily): Polyommatus (Genus): coridon (Species):
Description
The male Chalkhill Blue is a pale shiny sky-blue colour. Its wing edges have a dark brown band... the rear wings with small spots and brown edge band fringed with white. It is one of the largest blue butterflies in the UK. The males fly just above the vegetation searching for females. Large numbers of males may congregate on animal dung and moist soil where they feed on minerals.

The female is much less conspicuous being a dark chocolate brown colour and more secretive in behaviour, spending less time than the males in flight.

Habitat
The Chalkhill Blue is found on short calcareous grassland in Southern England where the larval food plant Horseshoe Vetch together with a population of ants. The ants protect the pupae in their nests in return for sugars and proteins which the caterpillars and pupae produce.

Larval Food Plants
Horseshoe Vetch (Hippocrepis comosa)
Stock Photography Library
We have 36 photographs of the Chalkhill Blue in the British Butterflies photo library
More photographs available
Image ID BB1920 - Chalkhill Blue - © Steven Cheshire
BB1920 - Chalkhill Blue
DSC_7929.JPG 		Image Licence Price List
Image ID BB1919 - Chalkhill Blue - © Steven Cheshire
BB1919 - Chalkhill Blue
DSC_7922.JPG 		Image Licence Price List
Image ID BB1918 - Chalkhill Blue - © Steven Cheshire
BB1918 - Chalkhill Blue
DSC_7864.JPG 		Image Licence Price List
Image ID BB1917 - Chalkhill Blue - © Steven Cheshire
BB1917 - Chalkhill Blue
DSC_7792.JPG 		Image Licence Price List
Image ID BB1916 - Chalkhill Blue - © Steven Cheshire
BB1916 - Chalkhill Blue
DSC_7762.JPG 		Image Licence Price List
Image ID BB1915 - Chalkhill Blue - © Steven Cheshire
BB1915 - Chalkhill Blue
DSC_7720.JPG 		Image Licence Price List
Image ID BB1914 - Chalkhill Blue - © Steven Cheshire
BB1914 - Chalkhill Blue
DSC_7684.JPG 		Image Licence Price List
Image ID BB1913 - Chalkhill Blue - © Steven Cheshire
BB1913 - Chalkhill Blue
DSC_7675.JPG 		Image Licence Price List
More photographs available
More photographs available
Distribution  
Distribution of the Chalkhill Blue shown in dark green.
Where to see the Chalkhill Blue
Cambridgeshire: Devils Dyke
Bedfordshire: Totterhoe Quarry
Hertfordshire: Therfield Heath
Gloucestershire: Prestbury Hill
Dorset: Corfe Castle, Fontmell Down, Ballard Down, Cerne Abbas Giant, Badbury Rings
Isle of Wight: Bonchurch Down, Compton Down
Wessex: Martin Down, Old Winchester Hill
Population Trends
species status the Chalkhill Blue is a resident species in Britain
population trend1 (1995-2004) down by -34% (1976-2004) up by 31%
1Fox, R., Asher. J., Brereton. T., Roy, D & Warren, M.
(2006) The State of Butterflies in Britain & Ireland, Pices, Oxford.
UK Biodiversity Action Plan (BAP) Status
UK BAP status2 species of conservation concern (link)
2 For more information about the UK Biodiversity Action Plan (BAP) species status, visit www.ukbap.org.uk.
IUCN Category Status
IUCN category3 near threatened near threatened4
3 Fox, R., Warren, M & Brereton, T.
(2007) New Red List of British Butterflies. Butterfly Conservation, Wareham.

4 More information about IUCN categories available here.
Find Out More Online*
More information about the Chalkhill Blue can be found on Peter Eeles excellent UK Butterflies web site.
Aberrations and Forms
We currently know of 87 named aberrant forms of the Chalkhill Blue. More information about aberrants can be found here.
ab. addenda - Tutt (1909)
ab. alba - Bright & Leeds (1938)
ab. albescens - Bright & Leeds (1938)
ab. albocuneata - Bright & Leeds (1938)
ab. albomaculae - Bright & Leeds (1938)
ab. alternafimbriata - Bright & Leeds (1938)
ab. anticaeca - Bright & Leeds (1938)
ab. anticrassilunulata - Bright & Leeds (1938)
ab. antidecrescens - Bright & Leeds (1938)
ab. antidiscoelongata - Bright & Leeds (1938)
ab. antidiscoradiata - Bright & Leeds (1938)
ab. antiextrema - Bright & Leeds (1938)
ab. antiglomerata - Bright & Leeds (1938)
ab. antiobsoleta - Bright & Leeds (1938)
ab. antiobsoletissima - Bright & Leeds (1938)
ab. antipluripuncta - Bright & Leeds (1938)
ab. antiradiata - Bright & Leeds (1938)
ab. antisagittata - Bright & Leeds (1938)
ab. atrescens - Tutt (1910)
ab. aurea - Bright & Leeds (1938)
ab. aurotithonus - Tutt (1910)
ab. caerumaculae - Bright & Leeds (1938)
ab. castanea - Tutt (1910)
ab. chlorescens - Tutt (1910)
ab. cinnameus - Bright & Leeds (1938)
ab. corydonis - Bergstrasser (1779)
ab. crassipuncta - Tutt (1910)
ab. discoidalisnulla - Bright & Leeds (1938)
ab. extrema - Bright & Leeds (1938)
ab. fowleri - South (1900)
ab. fumidescens - Bright & Leeds (1938)
ab. glabrata - Bright & Leeds (1938)
ab. grisea - Tutt (1910)
ab. impar - Cockayne (1916)
ab. inaequalis - Tutt (1896)
ab. increscens - Bright & Leeds (1938)
ab. i-nigrum - Tutt (1910)
ab. irregularia - Bright & Leeds (1938)
ab. khaki - Bright & Leeds (1938)
ab. livida - Bright & Leeds (1938)
ab. lucretia - Gaschet (1877)
ab. lunulata - Tutt (1909)
ab. melaina - Tutt (1910)
ab. metallica - Bright & Leeds (1938)
ab. minutissimus - Tutt (1910)
ab. mixtaalbocincta - Bright & Leeds (1938)
ab. nigrescens - Bright & Leeds (1938)
ab. obsolescens - Tutt (1910)
ab. obsoleta - Bright & Leeds (1938)
ab. ochracea - Frohawk (1938)
ab. ochrea - Bright & Leeds (1938)
ab. opposita - Tutt (1909)
ab. ornamenta - Bright & Leeds (1938)
ab. pallida - Tutt (1910)
ab. pallidula - Bright & Leeds (1938)
ab. parallela - Courvoisier (1907)
ab. parvipuncta - Courvoisier (1907)
ab. polonus - Zeller (1845)
ab. postaurantiaextensa - Bright & Leeds (1938)
ab. postcaeca - Bright & Leeds (1938)
ab. postdiscoelongata - Bright & Leeds (1938)
ab. postobsoleta - Bright & Leeds (1938)
ab. postobsoletissima - Bright & Leeds (1938)
ab. postradiata - Bright & Leeds (1938)
ab. postradiosa - Bright & Leeds (1938)
ab. postsagittata - Bright & Leeds (1938)
ab. pulla - Bright & Leeds (1938)
ab. punctata - Tutt (1896)
ab. radiata - Bright & Leeds (1938)
ab. radio - Bright & Leeds (1938)
ab. semialbescens - Bright & Leeds (1938)
ab. semibi-i-nigrum - Bright & Leeds (1938)
ab. semilimbojuncta - Bright & Leeds (1938)
ab. seminigra - Preissecker (1906)
ab. semisyngrapha - Tutt (1896)
ab. suffescens - Bright & Leeds (1938)
ab. suffusa - Tutt (1896)
ab. supraalbocrenata - Bright & Leeds (1938)
ab. supramelaina - Bright & Leeds (1938)
ab. syngrapha-inframarginata - Bright & Leeds (1938)
ab. transformis - Bright & Leeds (1938)
ab. ultracaerucrenata - Bright & Leeds (1938)
ab. ultrafowleri-margino - Bright & Leeds (1938)
ab. ultrainaequalis - Bright & Leeds (1938)
ab. ultramelaina - Bright & Leeds (1938)
ab. ultranubila - Bright & Leeds (1938)
ab. ultraviridescens - Bright & Leeds (1938)
References
The information on this web site comes from a variety of freely available resources including books, academic reports and web sites alongside my own personal observations of butterflies. The species descriptions are currently in the process of being edited (spring 2009) to include new data, recent personal observations and referencing following a major update to the site. A complete list of references mentioned in the text on this web site is available here.
* External Links Disclaimer
This web site includes links to information provided by external web sites which are not in any way under the control of www.britishbutterflies.co.uk. We cannot, therefore, be held responsible for the content of external web pages.
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