Soldierflies
Stratiomyidae
Soldierflies are a diverse family of flies, with around 50 species recorded in Britain. Clubbed General, Orange-horned Green Colonel and Dark-winged Soldier are three examples of rare British soldierflies whose larvae depend on high-quality wetland habitats.
- Clubbed General soldierfly by Judy Webb
Description/identification
Soldierflies are a diverse family of flies, with around 50 species recorded in Britain. Adults are distinctive, with some species displaying bright green, yellow or metallic markings. They often rest on foliage or visit flowers for nectar. Their larvae are typically elongated and legless, with a tough, leathery-looking body that is often flattened and distinctly segmented.
Clubbed General (Stratiomys chamaeleon), Orange-horned Green Colonel (Odontomyia angulata) and Dark-winged Soldier (Oxycera analis) are three examples of rare British soldierflies whose larvae depend on high-quality wetland habitats. All three are Nationally Rare. Clubbed General is classified as Endangered in Great Britain, while Orange-horned Green Colonel and Dark-winged Soldier are classified as Vulnerable. Although all three are associated with base-rich wetlands, their habitat requirements differ.
Clubbed General is a relatively large yellow-and-black species. It is highly specialised and occurs in calcareous fens, tufa-rich springs, seepages, runnels and shallow pools. Its larvae occur in calcium-rich water, often among stoneworts and sediment.
Orange-horned Green Colonel is a smaller green-and-black species, occurring principally in long-established fens, wet commons, pingo pools and base-rich mires. Its larvae inhabit well-vegetated margins of shallow pools and can occur in sites that become seasonally dry.
Dark-winged Soldier is associated with calcareous springs, streams, seepages, fens and wet woodland. Its larvae typically live in very shallow water or thin films of water over wet silt and other substrates.
Habitat
Soldierflies occupy a wide variety of habitats which typically include fens, marshes, wet meadows, seepages and flushes, pond and ditch margins, springs, reedbeds, wet woodland, and the margins of streams and rivers. Some species also occur in drier habitats, woodland or decaying organic material.
Life Cycle
Eggs are generally laid during the adult flight period, often on vegetation or other substrates close to suitable larval habitat. After hatching, larvae develop in habitats such as shallow water, saturated mud, wet moss, organic sediments and among aquatic or emergent vegetation.
Larval development of many UK species may extend over more than one year, with the larvae of Clubbed General (Stratiomys chamaeleon) potentially taking three or four years to develop.
Distribution and threats
In the UK many species – particularly the scarcer ones – are strongly associated with wetlands and other damp habitats. These rare soldierflies have restricted and often highly fragmented distributions in Britain, reflecting the scarcity of suitable wetland habitats. Sites supporting populations can therefore be of considerable conservation importance.
The three species have different British ranges. Clubbed General has become highly restricted in three remaining areas, one each in England, Wales and Scotland. Orange-horned Green Colonel is reported from Oxfordshire fens, the New Forest and East Anglia. Dark-winged Soldier is scattered across southern England and has become more restricted in recent years. Oxfordshire is especially significant, as Cothill Fen and nearby wetlands have records of both Clubbed General and Orange-horned Green Colonel.
Because many scarce soldierflies have specialised ecological requirements, their presence can also provide a useful indication of high-quality wetland habitat. Protecting and restoring suitable hydrology, water quality and diverse wetland microhabitats is therefore important for their long-term conservation.
Their dependence on clean water, suitable hydrology and specialised wetland microhabitats makes them vulnerable to environmental change. Main threats include habitat loss and fragmentation, drainage, water abstraction, pollution and nutrient enrichment, as well as inappropriate vegetation or wetland management. Climate change and increasingly frequent drought may also create additional pressures by causing shallow pools, seepages and other larval habitats to dry out.