Large blue butterfly  (Maculinea arion)

This chief reason for the decline of this species is loss of its habitat and scrub encroachment through lack of grazing. The life-cycle of the butterfly is complex and was not fully understood until after it had been lost from Britain. The red ant that supports the large blue butterfly requires a habitat which has few tall plants, is well grazed and where the surface temperature of the ground is warm. The loss of this habitat in many areas led to a drastic reduction in ant numbers and this, coupled with a major reduction in the populations of wild thyme, led to the extinction of the butterfly.

A co-ordinated approach toward conserving the large blue butterfly began in 1962 when a joint committee was formed. The committee was successful in finding colonies of butterflies but failed to discover any information concerning the relationship with the ant or the decline in ant numbers. The large blue butterfly was declared extinct in Britain in 1979. A decision was made to attempt re-introduction of the species and the butterfly was given special protection in 1975. In 1983 a re-introduction programme began with the importing of wild stock from Sweden. Further numbers were brought over in 1986 and in 1991 a five year recovery project was launched as a partnership under English Nature's Species Recovery Programme, together with the Institute of Terrestrial Ecology and the British Butterfly Conservation Society. So far suitable habitats have been re-created on all the earmarked sites and the large blue butterfly has been successfully re-introduced to several of them. As a bonus a significant increase in the numbers of another species of butterfly, the small pearl-bordered fritillary, have been recorded.