Northern Devon sand dune invertebrate group

In the UK this beetle is confined to a series of dune systems along the south Wales coast, Braunton Burrows and Woolacombe Warren, meaning Devon holds the only known English population. Larvae feed on the roots of vegetation in sand dunes. 

As with all click beetles, D. equisetioides have a notch on their spine that can snap together and propel the beetle into the air with a loud clicking sound. This can be used to right themselves if flipped over or to evade predators. 

In Britain this wetland snail is only known from Devon and Cumbria. In Devon it is found at Braunton Burrows and Northam Burrows where it lives on sparsely vegetated sand and mud in dune slacks, which are at least seasonally flooded (with freshwater).  

The Devon population has declined by 44% in the past two decades. At Braunton Burrows, some of the slacks formerly used have become overgrown by grassland, dense stands of creeping willow and scrub. A 2022 survey located populations of the snail in just two slacks. Some open areas are maintained by scrape creation.   

A subpopulation has recently been found on Northam Burrows. The active mixed grazing is maintaining short swards and this, with the creation of new scrapes for water germander (see the Sand dune plants group), has increased the extent of suitable habitat.  

The north Devon sand dune systems, most notably Braunton Burrows, are of outstanding importance for true flies and support numerous nationally rare and nationally scarce species, including at least five that are threatened, or near threatenedA species likely to qualify for threatened category in the future, perhaps very quickly. More, with extinction in the UK. These five aren’t known from anywhere else in Devon and are listed below (for more details on status see the Devon Species of Conservation Concern spreadsheet).  

This group of flies is strongly associated with early successional habitats – shifting sand, open slacks (damp hollows),  ponds and short, flower-rich grassland. They include: 

• The spurge bug parasite fly  (Dionaea aurifrons) is only known in the UK from Braunton Burrows and Woolacombe 

• Lispe consanguinea was re-found in 2023 where a small stream enters Croyde dunes. It hasn’t been recorded from other UK sites since 1960.  

• Helina parcepilosa was last recorded in Braunton Burrows in 2019 and is confined to a few dune systems in SW England and south Wales but with few post 1960 records. 

• Coenosia vibrissata was recorded from Braunton Burrows in 2016 and is known from a few locations in southern England on coastal dunes and damp patches in inland heaths.   

• Thrypticus lichanus is found at Braunton Burrows and is associated with shallow ponds with rushes (Eleocharis and Schoenoplectus). Elsewhere its known from single sites in Norfolk, Cambridgeshire, Dorset and Cornwall. 

This group also includes a few species that are, for flies, large and spectacular, such as the dune villa bee-fly (Villa modesta) and the dune robberfly (Philonicus albiceps). These can be used to help engage the public and increase awareness. The pied-winged robberfly (Pamponerus germanicus) has not been seen on Braunton Burrows since the year 2000. 

Note that a full review of flies at these dune systems and others (Braunton Burrows is by far the best recorded site as surveys of other sites are rare) is likely to uncover more threatened or near threatened species. There are also many species occurring on the sites that have yet to have their national status assessed, even provisionally.   

Little is know about changes to the distribution and population of flies in this group due to lack of records over time.  However, they are likely to have declined due to scrub encroachment, lowering of the water table, changes in grazing and reduced dynamism with the dune systems. See Pressures above. Restoration of dynamic processes, whether by mechanical intervention or increased grazing, is a priority.  

See the LNRS profile for sand dune flies in Find out more for more details. 

A number of rare moths are found in sand dunes and primarily recorded in Devon at Braunton Burrows, Northam Burrows and Dawlish Warren. The habitats used by these moths are often very specific and may often not be recognised as being of wildlife value. This focus group includes 10 species which are Devon Species of Conservation Concern. 

• Pancalia schwarzella  In England this moth is only known to occur at Braunton Burrows. Caterpillars have been found feeding on the leaves of heath dog violet, hairy violet and wild pansy and living in silken tubes spun amongst the moss Homalothecium lutescens.  

• Silverweed borer (Monochroa elongella): A micro moth. Caterpillars feed on the roots of silverweed, causing the plant to wilt. They have only been recorded in Devon at Braunton Burrows.  

• Coast Straw  (Gynnidomorpha permixtana): A micro moth. Caterpillars have been found feeding on the seeds of red bartsia.  The coast straw is known from scattered locations around the British coast and has been recorded at Braunton Burrows.  

• Shore knot horn (Gymnancyla canella): A micro moth. Caterpillars feed on prickly saltwort. They initially feed internally in the stems or shoots and then feed from within a silken web attached to the plant, containing trapped grains of sand.  In Devon this species has only been found at Dawlish Warren. 

• Sandhill knot horn (Anerastia lotella): A micro moth which is only found in sand dunes. The caterpillars feed on sandhill grasses, such as marram, where they construct a silken gallery around the stem bases and roots. They fly in July. Recorded in  northern Devon dunes, Dawlish Warren and Thurlestone in south Devon. 

• Saltern grass-moth (Pediasia aridella): A micro moth. Caterpillars feed on common salt-marsh grass in a silken gallery among the stem bases. They have been recorded in Braunton Burrows, and Northam Burrows. 

• Rolled grass-moth (Pediasia contaminella):  Caterpillars feed on a range of grasses but largely sheep’s fescue. Only found on the south Devon coast, especially around the Exe Estuary and at Dawlish Warren, 

• White colon (Sideridis turbida): Caterpillars feed on herbaceous plants in coastal areas and now largely confined to Dawlish Warren and north Devon sand dunes. 

• Shore wainscott (Mythimna litoralis). Like sandhill knott horn this species feeds on marram grass and is found in the same locations. 

• Sand dart (Agrostis ripae): Caterpillars feed on prickly saltwort and sea rocket. Found mainly at Dawlish Warren and dunes in northern Devon.