Start Point to Bolt Tail invertebrates group

The six-banded nomad bee was once widely distributed across southern Britain but is now Britain’s rarest bee, restricted to a single site along the coast at Prawle Point. 

Nomad bees are known as ‘cuckoo bees’ as they lay their eggs in the nests of other bee species. The six-banded nomad bee is dependent on the long-horned bee, which nests in bare soil on the warm, soft, south-facing cliffs and feeds on plants in the pea family such as everlasting pea, kidney vetch and other vetches and clovers. Long-horned bees are still present in this area but are thought to be declining due to loss of suitable habitat. They’re listed as a Devon Special Species as they’re critical for the six-banded nomad bee. 

The first British record of this robberfly was in 1990 at Woodcombe, near Prawle Point when several were seen on a footpath. It hasn’t been seen since but there’s a strong possibility that it survives somewhere along the coastal strip between Prawle Point and Start Point. It is hard to find due to the inaccessibility of much of the coastal slope and due to its short flight period. In 2012 a single male was recorded in Berkshire. In 2016 it was found on a hillside in Shropshire but hasn’t been seen again since 2020. It hasn’t been found anywhere else in England and is considered critically endangered. 

The robberfly lives on a mosaic landscape of small fields, soft cliffs, rank grassland, scrub and rocky knolls. It needs sandy soils and warm, open, south-facing slopes where it can bask on rocks in the sun. Its habitat is threatened by bramble and blackthorn, which due to a lack of grazing have increased considerably at Woodcombe and at many other similar coastal sites.  Management for the Devon red-legged robberfly is also likely to benefit the hornet robberfly (Asilus crabroniformis) a national conservation priority.

Nine species of rare spider live on the warm, sunny, sparsely-vegetated loose rocks and rocky fragments (known as ‘head deposits’) on the cliffs between Bolt Head and Froward Point. Like all spiders, they’re predatory, feeding entirely on other invertebrates, including ants. All the sites for this assemblageA group of different species that are found together in one place. More fall within either Prawle Point and Start Point SSSI or Bolt Head to Bolt Tail SSSI. No other county has records of all nine species in this assemblage.  

The rarest species is the moon spider (Callilepis nocturna), which is listed as a Devon Special Species. The jumping spider (Euophrys herbigrada) occurs more widely on the south coast between Cornwall and East Sussex. The ground spider (Micaria albovittata) has a similar range, and also occurs on some heaths a short distance inland. Other threatened spiders which occur here are also found in stony and sparsely-vegetated maritime grasslands. These are Acartauchenius scurrilis, Agroeca cuprea, Cozyptila blackwalli, Gnaphosa lugubris, Lasaeola prona, Phlegra fasciata and Zelotes longipes.  

Oil beetles are named for the bitter, oil-like fluid they produce from their knee joints to deter predators. All British oil beetles are parasites of solitary mining bees.  Female oil beetles lay eggs in batches of up to 1,000, in burrows they dig into sparsely-vegetated soil. The eggs hatch into larvae known as triungulins, which climb into flowerheads and hitch a ride on the backs of solitary bees. Once in the bee’s nest, the larvae feed on the bee’s eggs and stores of pollen and nectar. 

Oil beetles are largely found on flower-rich coastal grasslands where their host mining bees are found.