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Water boatman (Sigara)

Taxonomic group

Corixidae: Sigara

Diagnostic features

Sigara bugs are the well-known “water boatmen”, having long hair-fringed hind legs designed for swimming, and having forelegs ending in a trowel-like segment. The mouthparts are covered by a triangular, beak-like “labium”. Unlike the back swimmer Anisops, Sigara swims with its “belly” facing downwards

Typical habitats

Sigara can be common in slow-flowing streams, lakes, ponds and even in cow troughs.


Sigara use their trowel-like forelegs to scoop up food items including algae and organic detritus.

Indicator value

  • Hard bottom: 5
  • Soft bottom: 2.4

The tolerance values (ranging from 0 to 10) give an indication of which are the sensitive taxa (values of 8 or more) and which are the tolerant taxa (values of 3 or less). For more information see: Indicator species

An abundance of Sigara is likely to be the result of pond-like habitat conditions (at the site or upstream) rather than any particular water quality condition. They have medium to low tolerance values of 5 (hard bottom sites) and 2.4 (soft bottom sites).