Adonis blue  (Lysandra bellargus)

Males are bright sky blue in colour with a fine black line to the edge of the wings and a white border. Females are brown in colour becoming blue towards the body, with orange crescents towards the edges of the wings. Both males and females have pale brown undersides with black spots and orange crescents (1). The caterpillar reaches 1.6 cm in length, has a dark green body with dark spines (2), and yellow bands along the back and sides (1).

Found across Europe, in Britain the Adonis blue is at the northern extreme of its range (3), and has always been restricted to the warmer dry calcareous grasslands of southern England. It has suffered a huge decline in the last 200 years, and has been lost from Cambridgeshire, Essex, Suffolk, The Cotswolds, and The Chilterns. The main strongholds are Dorset, Wiltshire, Sussex (3) and the Isle of Wight (4). Over the whole of Britain there has been a huge decline of over 90% in numbers of this species since 1950 (5).

Inhabits warm south-facing slopes in chalk or limestone grassland characterised by short turf, where there is plenty of the larval foodplant Horseshoe vetch (Hippocrepis comosa) (3).

This species has two broods a year, there are therefore two adult flight periods; between mid-May and mid-June and early august to mid-September. Eggs are laid singly on the undersides of leaflets on small horseshoe vetches growing amongst short turf. The larvae feed on the underside of leaves, leaving typical feeding damage of small pale discs. Both larvae and pupae are always attended by ants, which are attracted by 'honey glands'. The ants provide protection against predation and parasitism and may even bury larvae at night! The larval stage over-winters, and emerges the following spring to complete development. Pupation takes place in the soil (3).

Many areas of suitable grassland have been removed by agricultural intensification, other sites have become degraded following abandonment or a decline in grazing, which maintains the short sward required by this species. In many sites a short sward was maintained solely by rabbit grazing, but the introduction of myxomatosis in the 1950s and the subsequent crash in rabbit populations led to a loss of short sward grasslands and a decline in the Adonis blue. After 1981, as rabbit populations have recovered and conservation measures have been put into action, the Adonis blue has made a partial recovery in some areas (5).

Many important sites for the Adonis blue have been designated as nature reserves, other sites have been targeted by agri-environment schemes such as Countryside Stewardship and Environmentally Sensitive Areas (ESAs) which have paid farmers grants to restore or increase livestock grazing. Despite these promising steps, in many areas the Adonis blue is still dependent on rabbit grazing, which can be unpredictable, to maintain a suitable sward height. Some sites are too small and isolated to support viable populations; horseshoe vetch is a poor coloniser and has been lost entirely from some former sites where there has been scrub invasion. The Adonis blue is a priority species under the UK Biodiversity Action Plan (UK BAP)(5).

For more information on this species see: Butterfly Conservation's Species Action Plan:
http://www.butterfly-conservation.org/species/action_plans/adonis_blue/index.shtml
For more on UK butterflies and their conservation see Butterfly Conservation,
http://www.butterfly-conservation.org/
And The Millennium Atlas of Butterflies in Britain and Ireland. Asher, Warren, Fox, Harding, Jeffcoate, and Jeffcoate. (2001). Oxford University Press, Oxford

Information authenticated by Butterfly Conservation:
http://www.butterfly-conservation.org/