The Purbeck mason wasp is a large, red, black-and-yellow mason wasp which provisions its nest with the caterpillars of a tortricid moth which feeds on heathers. The host caterpillar is commonest on plants of bell heather Erica cinerea in early to mid successional heathland. The flowers of bell heather are also the major nectar source for the adult wasps. The nest of the Purbeck mason wasp is dug in areas of bare, clayey ground within heathlands. The wasp flies between May and July.
This mason wasp has long been known to be restricted to a few lowland heathland sites in the Poole Basin area of Dorset. By the outbreak of the Second World War, it was known from seven different heathlands. Since the late 1940s, the range has contracted and, after the loss of the Stoborough Heath population in about 1980, the only remaining site appeared to be on Godlingston Heath NNR. A survey of clay exposures on Dorset heathlands carried out in 1995 and 1996 failed to find any further breeding sites for the species. In 1997, the monitoring programme revealed that the population size on Godlingston Heath had reached a very high level and, at the same time, new nesting aggregations were discovered on six other heathlands, all within the historic range of the species. The wasp is reported to be widespread in Europe. Although recent records from the near continent are lacking, it is not uncommonly found in the Mediterranean region (Turkey, Greek islands, France, Spain and Morocco). It is also reported from Canada, but the true status of this taxon remains uncertain.
In Great Britain this species is classified as Vulnerable.
The wasp became part of NE's Species Recovery Programme in 1996.
Six of the seven colonies recorded in 1997 are on SSSIs; the seventh is just outside one.
Action plan objectives and targets
Maintain populations at all known sites.
Enhance the population size at all known sites by 2010.
Restore populations to suitable sites to maintain ten viable populations within the historic range by 2010.
Proposed actions with lead agencies
Policy and legislation
Where appropriate, include the requirements of the species when preparing or revising prescriptions for agri-environment schemes. (ACTION: NE, MAFF)
Site safeguard and management
Where possible, ensure that all occupied and nearby potential habitat is appropriately managed by 2008, for example through SSSI or agri-environment scheme management agreements. (ACTION: NE, MAFF)
Ensure that the habitat requirements of the Purbeck mason wasp are taken into account in relevant development policies, plans and proposals. (ACTION: NE, LAs)
Ensure that this species is included in site management documents for all relevant SSSIs. (ACTION: NE)
Consider notifying sites supporting viable populations of the Purbeck mason wasp as SSSIs, where this is necessary to secure their long term protection and appropriate management. (ACTION: NE)
Species management and protection
If necessary to maintain ten viable populations, undertake habitat restoration and/or re-introductions at suitable former or potential sites. (ACTION: NE)
Advise landowners and managers of the presence of the species and the importance of beneficial management for its conservation. (ACTION: NE)
Future Research and Monitoring
Continue ecological research to establish the habitat requirements of this species and its prey, the factors limiting breeding success at existing sites, and its dispersal ability. (ACTION: NE)
Continue the current regular monitoring programme. (ACTION: NE)
Pass information gathered during survey and monitoring of this species to a central database for incorporation into national and international databases. (ACTION: NE)
Communications and Publicity
Promote opportunities for the appreciation of this species and the conservation issues associated with its habitat. This should be achieved through articles within appropriate journals, as well as by a publicity leaflet. (ACTION: NE)
Links with other action plans
Originally published in: UK Biodiversity Group Tranche 2 Action Plans - Volume IV: Invertebrates (March 1999, Tranche 2, Vol IV, p277)