Invertebrates Technical Factsheets from FWAG

Invertebrates of Flowing Water


Rivers and streams, although common, are extremely important as they have varied habitats within relatively short stretches, and serve as a link between other fragmented habitats especially in areas of intensive agriculture.

Fauna: e.g. Stream lacewing

The largest lacewing in Britain, found very locally beside shady streams. Adults can be found resting under bridges. The larvae live in damp moss on the edges of streams, often under overhangs, and feed on other invertebrates. Widespread in lowland Britain, more common in the west.

Stream lacewing (Osmylus fulvicephalus)


Many of the invertebrate species of flowing water perform vital tasks such as recycling dead material, predation of pest species (such as aphids) and pollination. They also have an important place in the food chain, supporting local populations of small mammals, birds, etc.

Beneficial management

  • Uncontrolled grazing leads to erosion and silting. If possible, fence off the majority of the bank leaving a small area for drinking access, this could be a concrete pad. Alternatively use a self perpetuating or solar pump.
  • Run-off of manures and inorganic fertilisers leads to nutrient enrichment of water and possible algal blooms. Do not spread manure within 10m or allow fertilisers to fall into water.
  • Be fully aware of LERAP spray requirements. Consider the establishment of extended field margins along watercourses.
  • Bare ground, sand, silt, gravel and shingle margins are very important for predating invertebrates. Do not remove sand, shingle etc from these areas.
  • Gravel-bottomed streams are especially important as spawning grounds for a wide range of fish and insect species.

Photo gallery 

Click <here> to view photographs of some important invertebrates of flowing water.

Further information

For further information including possible grant aid contact your local FWAG Adviser and visit the FWAG website at

Every effort has been made to ensure accuracy in the information sheet. However, FWAG cannot accept liability for any errors or omission.
Photographs Roger Key, English Nature
Author: Roger Key, English Nature
42.1 Jan 2004

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