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Guide to New Zealand's freshwater invertebrates
Water boatman
(
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.
Feeding
Sigara use their trowel-like forelegs to scoop up food items including algae and organic detritus.
Indicator value
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).
