THE ECOLOGY AND CONSERVATION OF THE SILVER-STUDDED BLUE BUTTERFLY PLEBEJUS-ARGUS L ON THE SANDLINGS OF EAST-ANGLIA, ENGLAND

Colonies of the locally rare and declining silver-studded blue butterfly Plebejus argus L. were studied on the Sandlings heathland, Suffolk, in 1985 and 1986. The extent of the Sandlings has been greatly reduced this century and is now very fragmented. Only one large colony was found to remain, representing half the total county population. Areas occupied were small, their protection poor and some are still threatened by development. Colonies are presently isolated and adults were found to be very sedentary in behaviour. The distances now separating heaths must greatly reduce the chances of new colonies being founded. Black ants Lasius sp. were involved in the life cycle from the point of egg hatching. Butterfly densities were (a) closely related to those of L. niger nests and (b) to the cover of bell heather Erica cinerea. Heaths were suitable when in an early stage of development, as a result of burning, disturbance or rabbit grazing, and the butterfly was absent from more vegetated areas or those dominated by ling Calluna vulgaris. The conservation of P. argus requires (a) a programme of monitoring the suitability of remaining heathland; (b) the retention and creation of correct habitat conditions through management; and (c) making correctly planned introductions to suitable sites. Preliminary studies are described. © 1990.