What Bug Is That? The guide to Australian insect families.

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The water boatmen bear a passing resemblance to the Notonectidae but may be distinguished from them by the shape of the forelegs, which are modified into hair-fringed scoops (called pala). Additionally water boatmen swim with their backs upward, as opposed to the Notonectidae which swim upside down. The Corixidae is the only family included in the superfamily Corixoidea.

The modification of the mouthparts in Corixidae is unique among the true bugs and reflects the more generalised feeding habits characteristic of this group. Using their scoop-like forelegs the Corixidae comb through the ooze and detritus at the bottom of water bodies. Here they ingest not only plant material such as algae, but whole organisms such as diatoms, protozoans, mosquito larvae, midge larvae and small crustaceans such as Daphnia . In effect, corixids feed on a soup of live and dead animal and vegetable material.

Corixidae can produce sound (stridulation) which can be heard if the insects are kept in an aquarium. In Australia there has been little work done on the function of stridulation, however research on overseas species indicates that stridulation is used in courtship, sometimes by both sexes. There is also some evidence that stridulation is used between males involved in disputes over territory or females.

Corixidae are one of the few groups of insects eaten by humans, especially in Mexico, where the adults bugs are sold at markets under the name 'Mosco'. Adults disperse to new water bodies by flying and are readily caught by entomologists at light traps.


The Australian Corixidae are represented by 31 species contained in four subfamilies and five genera. The subfamily Corixinae is distributed across all states and is represented by two tribes (Agraptocorixini and Corixini), two genera ( Agraptocorixa and Sigara ) and 13 species.The Cymatiainae is a small subfamily containing only one species, Cymatia ( Cnethocymatia ) nigra from north-east Queensland. The Micronectinae contains 14 species, all from the genus Micronecta .

  • Corixiidae (Heteroptera)

  • Agraptocorixa sp.