BR. J. EVT. \\T HIST.. 7: 19M * 



SOME RARE AND THREATENED KBS RFC ORDFD 

 FROM SALISBURY PLAIN, WD WiIRl 



G. R. Else 



Department of Entomology, The Satural History Museum, Cromwell Road, London SH^fBD 



and S. P. M. Roberts 



22 Belle Vue Road, Salisbury, fMtshire SP1 3YG. 



Introduction 



Salisbury Plain is located in south Wiltshire, extending westwards from tft i . 

 eastern border to Westbury and Warminster, and from the Vale Bey 10 miles 



south to the vicinity of Amesbury. Except for a few small villa;. - half 



of the region is sparsely inhabited, the main centres of population being the army 

 garrisons. The Plain is about the same size as the [sk of Wight, with va* 

 countryside designated as the Salisbury Plain Training .Area (S.P.T.A. >. the 

 of the Ministry of Defence (M.o.D.), and used primarily as artillery ran;, 

 training personnel. Much of the area cons - - ::' chalk grassland, with scru~ 

 isolated plantations. The S.P.T.A. encompasses the largest remaining ... 

 semi-natural chalk grassland in Europe (37,651 ha.) (McOmish & Field, 1993 S 

 of the grassland is mown annually for hay in late June and early July, an activity 

 which unfortunately coincides with the peak flight period of several of the rarer bees 

 in these areas, as many pollen and nectar sources are removed. 



Possibly because of its M.o.D. administration (permits are require, 

 the ranges), the region has been largely neglected by entomc . - r - - 

 has shown that Salisbury Plain has a very rich aculeate fauna (especially comr 

 those species characteristic of calcareous grassland), and includes a numb, 

 nationally rare or threatened species. The latter includes the bees Melitta dimidiata 

 Mor. and Xornada armaia H.-S.. both of which are accorded RDB1 status (i.e. they 

 are categorized as nationally endangered species in the insect Red Da 

 .v Spooner, 1987) and A review of the scarce .. . :ed bees, wasps one 



of Great Britain (Falk, 1991). In Britain M. dimidiata is known only : 

 grassland sites in Wiltshire. 



In the period 19S5-S5 a thriving population of M. dimidiata was fount 

 G. R. Else and M. Edwards on chalk grassland near Easton Royal in the Vale of 

 Pewsey. A subsequent search in this site on 25. \ i. 1°>S^ by both authors revealed only 

 a single male. None was encountered on further visits by us. the most recent in June 

 1 00 3. The bee had been found here first by K. M. Guichard on the 29.vii.1972 

 (Guichard. 19"3). This site is a small, isolated cutting, consisting 

 an adjacent steep grassy slope; the area is surrounded mainly by improved' sheep 

 pasture (a euphemism for artificially fertilized grassland which is deficient in 

 plants characteristic of chalk downland). The population crash seems to have been 

 due to rabbits which had eaten many of the sainfoin (Or. 



plants on which this bee solely relies for both pollen and nectar. Encouragingly this 

 plant had fully recovered to its former abundance by June 1993 



The depressing decline of this bee prompted us, in 1991. to undertake 

 of the four sites (all on Salisbury Plain) where the species had also been found in 

 the past, and to investigate other grassland sites on the Plain where sainfoin was i 

 established in the hope of finding further populations of M. dimidiata. As a result, 

 over the three seasons 1991-93. a most encouraging picture of the fortunes of this 



