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

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The water measurers or marsh treaders are semi-aquatic bugs. They have a distinctive head, being extremely elongate, extended both behind and in front of the eyes. The Hydrometridae is the only family found in Australia belonging to the superfamily Hydrometroidea.

Very little information is available on the biology and ecology of the Australian species of this family. Hydrometrids occupy a variety of habitats, usually in association with fresh water, though they are also known from brackish water. They prefer slow moving or still water where they can be found moving slowly across the surface of the water or on vegetation that has broken the surface of the water.

The Hydrometridae are primarily predators and scavengers, feeding upon aquatic invertebrates as well as the dead bodies of terrestrial invertebrates floating on the surface of the water. Cannabilism has been recorded in species that have been reared in the laboratory.


Only 6 species, all belonging to the subfamily Hydrometrinae and genus Hydrometra , are found in Australia.

  • Hydrometridae (Heteroptera)

  • Hydrometra sp.