HYMENOPTERA > APOCRITA | Aculeata > Vespidae > Eumeninae

This relatively large (9-13mm body length) distinctive black wasp, with dark orange markings, whiteish spots on the thorax and similarly coloured abdominal bands, is the only representative of its genus in Britain. It is restricted to a small handful of heathland sites in the Poole basin and Isle of Purbeck area of Dorset, and is a species that has always been regarded as both rare and threatened due to its very specific lifestyle requirements. It is dependent on areas of exposed ground with a suitable clay content for nesting, a good water source and heathland rich in bell heather where it can both nectar and hunt.

The Purbeck Mason Wasp is only active for a short time each year when it is nesting from mid-June to early August, or occasionally a bit later in the month. Shallow burrows are formed in sunny locations on bare ground with each burrow containing up to three nest cells. The nests are provisioned exclusively with the paralysed larvae of the Heath Button tortricid moth Acleris hyemana. At least a dozen larvae are stocked into each cell, and when all the cells are provisioned, the burrow entrance is sealed with a plug of moistened clay.