- Cyaniris semiargus semiargus (Europe, Caucasus, Siberia, Russian Far East)
- Cyaniris semiargus altaiana (Tutt, 1909) (Tian-Shan, Altai Mountains, Sayan Mountains, Transbaikalia)
- Cyaniris semiargus amurensis (Tutt, 1909) (Amur river, Ussuri, Japan)
- Cyaniris semiargus atra (Grum-Grshimailo, 1885) (Ghissar, Alai Mountains, Darvaz)
- Cyaniris semiargus jiadengyunus (Huang & Murayama, 1992) (Altai Mountains)
- Cyaniris semiargus maroccana (Lucas, 1920 (Morocco)
- Cyaniris semiargus tartessus (Gil-T. & Huertas, 2007) (SW. Spain)
- Cyaniris semiargus transiens Melcon, 1910 (Spain)
- Cyaniris semiargus uralensis (Tutt, 1909) (Urals)
The Mazarine blue's population is distributed throughout continental Europe, reaching into the Arctic Circle , Morocco, and the Middle East  then east across the Palearctic to Siberia and the Russian Far East. There was a large native population in Britain in the early part of the 19th century, but it disappeared before the 20th century, though single vagrants have been spotted, and some estimates of British resident extinction are as late as 1906. In 2009, UNESCO was researching a possible British reintroduction of the Mazarine blue to Britain. Recently, the Mazarine blue's numbers have been declining in its European range (particularly Scandinavia) and the reason remains unclear.
This common species inhabits meadows, pastures, grasslands and flowery grassy damp areas up to 2200m. It seems to prefer places which are not fertilized and not used for fodder production.
These butterflies present a sexual dimorphism. The male Mazarine blue's wings are a deep blue with a heavy venation and are slightly larger in diameter than the female's. The upperside of the wings shows black borders and white fringes. The female Mazarine blue is brown. The underside of the wings is greyish or ocher, with a series of black spots surrounded by white and a blue scaling in the basal area.
This species is rather similar to Cupido minimus, but in the underside hindwings of the Mazarine blue the black spot in space 6 and the two spots next to it form an obtuse angle, while in C. minimus they create an acute angle.
This species has one brood each year. It overwinters as a young larva. Adults fly from May to August. Caterpillars mainly feed on Red Clover (Trifolium pratense) and other species of Trifolium (Trifolium medium, Trifolium spadiceum), on Vicia cracca, Anthyllis, Genista and Melilotus.
- D.J. Carter (ill. B. Hargreaves), Guide des chenilles d'Europe, Delachaux et Niestlé, coll. «Les guides du naturaliste », 2001, 311 p. (ISBN 2-603-00639-8)
- Gil-T., F. & M. Huertas (2007): Description of Cyaniris semiargus tartessus subspec. nov. from the National Park of Doñana (SW. Spain) (Lepidoptera, Lycaenidae). ISSN 0171-0079 | Atalanta, 38(1/2): 185–188. Full article: .
- Haworth (1803) Haworth, A.H. (1803) Lepidoptera Britannica.
- Leach (1815) Leach (1815) In Brewster: The Edinburgh Encyclopædia.
- Lewin (1795) Lewin, W. (1795) The Papilios of Great Britain.
- Swainson (1827) Swainson, W. (1827) A Sketch of the Natural Affinities of the Lepidoptera Diurna of Latreille. The Philosophical magazine : or Annals of chemistry, mathematics, astronomy, natural history and general science.
- Tolman T., Lewington R. Collins Field Guide Butterflies of Britain & Europe — London : Harper Collins Publishers, 1997.— 320 p., 106 col. Pl
- Tom Tolman et Richard Lewington, Guide des papillons d'Europe et d'Afrique du Nord, Delachaux et Niestlé, 2010 (ISBN 978-2-603-01649-7)
- Fauna europaea
- Recorded for example, in Syria Graves, Philip P. (1905). "Notes on Egyptian and Syrian butterflies". The Entomologist's Record and Journal of Variation. 19.
"Specimens: Cyaniris semiargus". www.theinsectcollector.com. Retrieved 2010-07-03.
Locality: Morocco Sub Species: maroccana
Eeles, Peter (2002). "UK Butterflies - Mazarine Blue - Cyaniris semiargus". www.ukbutterflies.co.uk. Retrieved 2010-07-03.
first mentioned as British in 1710 and there are several hundred sightings recorded up until the late 19th century. Various dates are given for the last sighting, although all are linked with a particular region. The end of the 19th century seems to mark a watershed, after which there are very few records.
Dennis, Roger (1994). Butterflies and climate change. Manchester University Press. p. 134. ISBN 978-0-7190-4033-7. OCLC 27339355.
four species have become extinct [in Britain] (i.e. Lycaena dispar 1851, Cyaniris semiargus 1877, Aporia crataegi c. 1925, Maculinea arion 1979).
Watson, L. (2008). "British Insects: Butterflies - Lycaenidae". delta-intkey.com. Retrieved 2010-07-03.
Cyaniris semiargus (Mazarine Blue - extinct, now occasionally adventive)
- "How many species have gone extinct in the last 100 years?". www.jncc.gov.uk. Retrieved 2010-07-03.
- "The UNESCO strategy for Action on climate change" (PDF). unesdoc.unesco.org. Retrieved 2010-07-03.
- Simon Coombes Captain's European Butterfly Guide
- "UK Butterflies - Mazarine Blue - Cyaniris semiargus". Retrieved 2010-07-03.
- "Cockayne Collection". Natural History Museum. Retrieved 2010-07-03.
- Matt Rowlings Euro Butterflies
- "Mazarine Blue (Polyommatus semiargus) - Lycaenidae - Lepidoptera - Insecta - Wildaboutdenmark.com". www.fugleognatur.dk. Retrieved 2010-07-03.
- Kimmo Silvonen Larvae of North-European Lepidoptera
- Stokoe, W.J. (1962). Observer's Book of Butterflies. Frederick Warne. p. 131.
- Paolo Mazzei, Daniel Morel, Raniero Panfili Moths and Butterflies of Europe and North Africa