64 BR. J. ENT. NAT. HIST., 7: 1994 



bumblebees— Psithyrus species) have been found on Salisbury Plain. Of these ten, 

 B. humilis 111., B. lapidarius (L.), B. ruderarius (Miiller) and B. sylvarum (L.) are 

 associated mainly with dry, calcareous grassland in southern England. An abraded 

 queen of B. ruderatus was found just north of Tilshead on 27. vi. 1992 by G. R. E. 

 (the only specimen he has encountered anywhere in the past 24 years). 



B. ruderatus was formerly a common and widely distributed species in Britain, the 

 range extending from Kent to Cornwall, northwards to Northumberland (Else, in 

 prep.); in Wales there is an old record from southern Gwynedd (see map in Anon., 

 1980). Sladen (1912) mentions that the species occurs in Scotland, and also cites a 

 single Irish record. These old records cannot be confirmed and may be based on 

 misidentifications. There can be no doubt that this bumblebee has declined dramatically 

 this century. To Sladen it was a very common bee in England (his 'Large Garden 

 Humble-bee'), but today it is rarely encountered, most other recent records originating 

 from east Kent (P. Williams, pers. comm.) and East Anglia (S. Falk, pers. comm.). 

 Even in these localities the species is very scarce. The British flight period of the species 

 is from mid April to mid October. 



B. sylvarum (L.). Although formerly widespread in southern Britain, the range 

 of this bumblebee has diminished greatly in recent years. It has been recorded from 

 Kent to Cornwall, northwards to Gwynedd, southern Cumbria and Northumberland 

 (Anon., 1980). It is a rare and sporadic bee in Ireland, with only a single confirmed 

 Scottish record. It occurs in various biotopes, but especially in chalk grassland. On 

 Salisbury Plain it was found near White Barrow, in July 1983 and June 1984; and 

 north of Tilshead in July 1991 and June 1992. R. Gabriel found the species on 

 the east side of the West Lavington road (opposite Horse Down), 1 kilometre 

 to the north-west of Tilshead, on 16.vii.1993. The national flight period is from mid 

 May to September. 



Psithyrus rupestris (F.). Formerly this cuckoo bumblebee was found throughout 

 much of the British Isles, except for the far north of Scotland, the Scottish Islands 

 and the Isle of Man (Else, in prep.). During this century the species' range has 

 contracted dramatically, so that currently the bee is largely restricted to sites in southern 

 England and Wales, and coastal Eire (Anon., 1980). Even in these areas the bee 

 is very sporadic. The reason for the decline is unknown. The species is a social 

 parasite of Bombus lapidarius, a bumblebee which remains common and widespread 

 throughout much of the British Isles. In the past Sladen (1912) estimated that in east 

 Kent females of P. rupestris usurped 20-40% of B. lapidarius nests. Nationally, this 

 cuckoo bumblebee flies from late May to late September. 



In recent years this species has been found in several sites on Salisbury Plain: 

 Parsonage Down, near Winterbourne Stoke, a male, 17.vii.1982; Great Cheverell Hill, 

 many females, 6 and 20. vi, one female 4.vii, and several males 21 .viii. 1993; Bulford, 

 female, 6.vi.l993; near Tilshead, several females, 27. vi (unusually one had a bright 

 yellow pronotal hair band) and l.vii.1993, and a male 21. viii. 1993. 



Acknowledgements 



We would like to thank D. B. Baker, M. Edwards, R. Gabriel, K. M. Guichard, 

 S. R. Miles and D. Sheppard for allowing us to publish records of their observations 

 of aculeates from Salisbury Plain. We are also grateful to the late I. H. H. Yarrow 

 and the late G. M. Spooner for their records. Two Wiltshire botanists, Audrey 

 Summers and Barbara Last, kindly provided information concerning the distributions 

 of sainfoin and scabiouses on the Plain and encouraged us to look at the Wiltshire 

 Wildlife Trust reserve at Great Cheverell Hill. D. E. Coombe, O. Rackham and 



