Wet woodlands are found across Devon but are particularly frequent on the heavy, wet, clay soils of the Culm Measures that occupy the land between Dartmoor, Exmoor and the Atlantic coast. Other key areas are the edges of Dartmoor National Park, where they often occur together with Rhos pastures, and the spring-lines of the Blackdown Hills.
Devon’s wet woodlands support an exceptional range and abundance of fly species. One wet woodland in west Devon has recently been estimated to produce 38 million flies per hectare per year. They support many nationally rare or scarce flies, including four listed as Devon Species of Conservation Concern. Three are considered vulnerable to extinction in Britain (Macrocera longibrachiata, Neoempheria winnertzi and Rhaphium fascipes) and one is near threatened (Coenosia pudorosa). See the Devon Species of Conservation Concern spreadsheet.
Other species in this group include Egle parvaeformis, which is Near Threatened, and four Nationally Scarce species: the Liverwort Snipefly (Spania nigra), the Sooty Blacklet Hoverfly (Cheilosia carbonaria), the Rust Fly (Chyliza vittata) and the Lesser Housefly (Fannia speciosa). See Find out more below for a link to the more detailed wet woodland fly group profile and a list of all species in this group.
Flies in this group are strongly dependent on conditions relating to the water in wet woodlands, such as its quality, quantity and flow. In Devon, key impacts include land drainage and pollution (mainly from fertiliser run-off). Climate change, especially the increasing frequency and severity of summer droughts, poses a major threat to this group as fly larvae depend on continuously moist conditions.
Flies can also be at risk from lack of grazing. Wet woodlands are often permanently fenced off from adjacent wet grasslands because it’s thought that this will benefit their wildlife. However, research in Devon shows that the fly population is likely to be more diverse and richer in scarce species when there is some cattle grazing.
See the Wet woodland page for more information.
Actions
Manage, restore and create a network of wet woodlands as part of a dynamic mosaic of habitats. Maintain and restore natural hydrological processes in and around wet woodlands (water flows, quantity and quality) and where appropriate lightly graze with cattle to maintain a range of microhabitats.
Identify key sites for flies and other invertebrates and bring them into favourable management. Periodically survey key wet woodlands to determine the health of the rare fly population, particularly to check whether key species are present.
See the Wet woodland page for more actions and information.
Where to focus action
High Opportunity Areas: Ancient and broadleaved woodlands (existing) which contain wet woodlands. North Devon Culm, Dartmoor Rhos Pastures, East Devon Spring-Line Mires.
Wet woodland flies will benefit from these actions being implemented across Devon. Note that there is not currently a map of wet woodlands for Devon.