Butterflies of the World - Lifecycle, Ecology, Taxonomy, Conservation, Photography, Butterfly Holidays, Photo Galleries, Book Reviews and more.........
Text and photographs protected by Copyright © Adrian Hoskins 2007, and must not be published in part or in whole elsewhere without prior written permission from the author.
Butterflies of Britain & Europe
 
Chalkhill Blue
Lysandra coridon PODA, 1761
Family - LYCAENIDAE
subfamily - POLYOMMATINAE
 
 introduction | habitats | lifecycle | adult behaviour
 
Chalkhill Blue Lysandra coridon, male, Magdalen Hill Down, Hampshire, England
 
Introduction
 
A freshly emerged male Chalkhill Blue is a particularly beautiful insect, with shimmering silvery blue wings, and long hair-like scales adorning the body, giving it a distinctly furry appearance. The female in contrast is a dull earthy brown, and easily overlooked.
 
Chalkhill Blue Lysandra coridon, male, Stockbridge Down, Hampshire, England
 
It is distributed across much of Europe, but absent from Scotland, Ireland, northern Scandinavia, Portugal, southern Spain and most of the Mediterranean islands. It's range extends into western Asia as far as the Ural mountains.
 
In Britain the female can be confused with the female Adonis Blue L. bellargus, but the upperside of the latter has a deeper chocolate ground colour. The emergence of the second brood of bellargus overlaps slightly with the emergence of coridon during August, and both species often share the same habitats.
 
In Europe there are several species which closely resemble both sexes of the Chalkhill Blue, and it is essential to consult a well illustrated field guide to differentiate between them.
 
Chalkhill Blue Lysandra coridon, male, Magdalen Hill Down, Hampshire, England
 
Habitats
 
The butterfly breeds on chalk and limestone hills, favouring south facing slopes where the larval foodplant horseshoe vetch grows profusely amongst fine grasses. The greatest numbers occur on sites that are heavily grazed by sheep, cattle or rabbits. The butterfly is capable however of surviving at low densities for many years at sites where grazing has been abandoned and the grasses grow tall. At such sites the butterflies breed in areas where the foodplant grows at the edge of paths, on patches of scree, or abutting rabbit scrapes.
 
Colonies are often very large, sometimes numbering several thousand individuals. In Britain it's range is restricted to the southern counties of England.
 
Males are often found up to 8kms from the breeding sites, sometimes in quite unsuitable habitats such as woodland clearings. Female strays are almost unknown. As a dispersal mechanism this is very unusual - in most species the females show greater powers of dispersal.
 
Chalkhill Blue Lysandra coridon, male, Stockbridge Down, Hampshire, England
 
Lifecycle
 
This species is single brooded, with a protracted emergence beginning in early July and continuing into late August.
 
The reticulated, dome-shaped off-white eggs are laid singly on the stems of horseshoe vetch Hippocrepis comosa or on nearby grass stems in August. During the winter they are washed off by the rains, and lie on the surface until the spring. The larvae are fully formed within the eggs in the autumn, but do not hatch until the following March.
 
The plump green larva is marked with broken yellow lines along it's back and sides. It rests beneath stones or chalk fragments during the daytime, and feeds nocturnally. It can be found easily at dusk, when large numbers of ants are in constant attendance.
 
Ants sometimes carry a larva, placing it closer to their nest, "milking" the larva for the sugary secretion exuded from it's "honey glands". In return for their reward, the ants protect the larva against predatory insects and arachnids.
 
The pupa is a dirty greenish colour, and is formed on the surface of the ground. Like the larva, it exudes sugary secretions, and attracts ants, which hide it by covering it with tiny fragments of earth.
 
Chalkhill Blue Lysandra coridon, male, Old Winchester Hill NNR, Hampshire, England
 
Adult behaviour
 
The butterfly, when it emerges in July, has to break through the soil and find it's way to a stem from which it can hang to dry it's wings. The adults often emerge en masse, and can sometimes be found basking in hundreds on low herbage early in the mornings.
 
Favourite nectar sources include marjoram, stemless thistle, carline thistle, knapweeds, wild basil, self heal and thyme, although they will also visit bramble, ragwort, yarrow and hemp agrimony. They also occasionally gather in small groups on mammal dung, and in alpine regions of Europe often congregate in thousands to drink at patches of mud or urine-soaked soil.
 
Chalkhill Blue Lysandra coridon, male, Stockbridge Down, Hampshire, England
 
Chalkhill Blue Lysandra coridon, male, Stockbridge Down, Hampshire, England
 
Chalkhill Blue Lysandra coridon, male, Magdalen Hill Down, Hampshire, England
 
As dusk approaches the butterflies migrate to the base of hills, where they roost over-night on tall grasses, often with several males sharing a single grass head, all resting in a head-downwards position.
 
Chalkhill Blue Lysandra coridon, female, Stockbridge Down, Hampshire, England
 
Chalkhill Blue Lysandra coridon, female, Stockbridge Down, Hampshire, England
 
                                                       
Almost every British and European species of butterfly is declining rapidly in numbers, due in most cases to loss or degradation of habitats.
 
You can help to reverse the decline by supporting conservation organisations which purchase and manage habitats as nature reserves, and which lobby government at local, national and international levels, often very successfully, to bring about changes in farming, forestry and urban development policies.
 
Please contact the conservation organisations for advice on how you can help protect British and European butterflies and their habitats. You may be able to offer practical help e.g. by monitoring butterfly populations or helping to manage nature reserves. Donations to these organisations enable them to employ ecologists and biologists. Even if you are unable to provide such help, merely having your name on the membership list can be a powerful tool for conservation organisations wishing to demonstrate the levels of support they have for their policies.

 

 
Text and photographs protected by Copyright © Adrian Hoskins 2007-2008, and must not be reproduced or published in part or in whole elsewhere in any form without written permission from Adrian Hoskins. Breach of copyright will be pursued by litigation.
 
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