Invertebrates Technical Factsheets from FWAG

Invertebrates of Still Water


A widespread habitat including farm ponds, seasonally wet ponds, flushes, slow running ditches especially in former wetland. Even puddles and wheel ruts create specialist conditions for invertebrates.

Fauna: e.g. water measurer

A very long, thin, frail-looking black bug, about 1.5cm long, which dwells on the surface of water. It feeds on other invertebrates, either hunting or taking advantage of organisms trapped in the surface film. Found at vegetated margins of all types of water body, where vertical emergent plant stems are available as egg-laying sites. Distributed throughout Britain; more common in the south.

Water Measurer (Hydrometa stagnorum)


Many of the invertebrate species of still water perform vital tasks such as recycling dead material and pollination. They also have an important position in the food chain, supporting local populations of small mammals, birds, etc.

Beneficial management

  • Do not allow pollution of ponds through run-off of manures, fertilisers or pesticides.
  • Take advice before restoring a pond and, if restoration is appropriate, do not clear all the pond or all the ditch system in any single year.
  • Do not introduce fish to ponds where they are currently absent, they will eat many invertebrate larvae etc.
  • Consider coppicing some overhanging trees or where trees shade out the sun.
  • Ponds that dry out naturally have their own specialist value and might not be appropriate for deepening to hold water all year.
  • Maintain stability of areas around still water.

Photo gallery 

Click <here> to view photographs of some important invertebrates of still 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
46.1 Jan 2004

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