Species Profile

Purbeck mason wasp (Pseudepipona herrichii)

Purbeck mason wasp © Chris Dresh (ARC).

Appearance/Colour

 Between 9 and 11 mm in length.  Black with ivory stripes and two distinctive orange patches on the abdomen.  Four white spots on the thorax.  Legs are mostly orange.  Short tongue.

Behaviour & Breeding

 Solitary wasp.  Males emerge from their winter diapause in early summer with the females emerging shortly after.  Flight period is from June to July where mating, feeding, collection of Heath Button Moth (Acleris hyemana) larvae and creation of nest burrows take place.  Adults feed on nectar from Bell Heather (Erica cinerea) by biting a hole in the base of the flower.  Once mated, the females begin excavating a shallow nest burrow in areas of bare ground containing 1-3 brood chambers within it.  Each brood cell is filled with a dozen or more larvae of the heath button moth before an egg is laid and the cell is sealed.  When the nest burrow is completed, the female will seal it with a plug of moistened clay so that it is perfectly camouflaged.  The males die after about 10 days, leaving all the work of excavating and provisioning to the females.  Nest burrows are distinctive with a circular entrance and a characteristic granular spoil heap of excavated soil deposited nearby.

Purbeck mason wasp © Chris Dresh (ARC).

Habitat/Where to find them

 Heathland, rich in early- to midsuccession Bell Heather (Erica cinerea) featuring exposed ground with a clay content and close to open water.  Restricted in Britain to a handful of heathland sites, such as ARC managed Creech heath, in and around Purbeck, Dorset.  Declines in numbers are linked to a reduction in the area of lowland heathland. In addition, land-use changes on the remaining heathland has resulted in a reduction in the number of suitable bare areas for nesting and appropriate heather swards for the moth caterpillars.

Feeding on nectar © Chris Dresh (ARC).

Status

 Endangered.  Species “of principal importance for the purpose of conserving biodiversity” under Section 41 (England) of the Natural Environment and Rural Communities Act 2006.