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 Major Groups | Insecta (insects) | Hemiptera (bugs) | Gelastocoridae


Major Group: Insecta
Genus: Nerthra
This family is represented in Australia by a single genus, Nerthra Say.

Descriptive Features:

  • antennae 4-segmented, short, not visible from above
  • eyes large, protruding and reniform
  • ocelli usually present
  • head subtriangular and somewhat depressed
  • rostrum 4-segmented, short, does not extend beyond forecoxae
  • pronotum large, transverse, wider than the head
  • scutellum triangular, large
  • ovoid body with a dull, roughened surface, often with a warty appearance
  • wing polymorphism common, with flight rare
  • in some species the hemelytra are fused along the midline
  • mid- and hindlegs slender, forefemora incrassate
  • fore tarsus cylindrical, with 1 or more segments
  • hind tarsi 3-segmented
  • Total length: 5.1 - 10.8mm

    Nerthra sp.

    Taxonomic Checklist: Species
    Nerthra adspersa Stal
    Nerthra alaticollis Stal
    Nerthra annulipes Horvath
    Nerthra appha Cassis & Silveira
    Nerthra elongata Montandon
    Nerthra falcatus Cassis & Silveira
    Nerthra femoralis Montandon
    Nerthra grandis Montandon
    Nerthra hirsuta Todd
    Nerthra hylaea Todd
    Nerthra luteovaria Distant
    Nerthra macrothorax Montrouzier
    Nerthra nudata Todd
    Nerthra monteithi Cassis & Silveira
    Nerthra plauta Todd 
    Nerthra polhemi Cassis & Silveira
    Nerthra probolostyla Todd
    Nerthra sinuosa Todd
    Nerthra stali Montandon
    Nerthra suberosa Erichson
    Nerthra soliquetra Todd
    Nerthra tasmaniensis Todd
    Nerthra tuberculata Montandon
    Nerthra walkeri Todd

    Distribution: Australia wide

    Sensitivity Rating: SIGNAL grade 5

    Functional Feeding Group: predators


    Mitta Mitta River, Eskdale Vic

    Ecology: Instream habitat: Commonly known as ‘toad bugs’ Gelastocoridae species occur on the ground and in the leaf litter in a variety of habitats, from both wet and dry sclerophyll forests to open heathland habitats. They are considers to be semi-aquatic species occurring in riparian and littoral areas of lentic water bodies or from very slow flowing areas of rivers. They are found under stones and plant debris or burrowing into wet sand or mud.
    Feeding ecology:Toad bugs are opportunistic predators and scavengers feeding on a variety of small aquatic and semi-aquatic insects. The roughened and mottled nature of the body provides a good camouflage (cryptozoic). Gelastocorid bugs manage a staggered run to seize prey, killing it with their needle-like mouthparts.
    Habit: Very little is known about the biology of Australian Nerthra species. Northern Hemisphere species seem to be nocturnal, hiding and resting during the day then crawling across wet or damp substrata at night to forage and hunt. Australian Gelastocoridae species are usually flightless with the wings either absent or greatly reduced.
    Life history: The life cycle is poorly known. Eggs are broadly oval, flattened on one side and the shell has a rough hexagonal sculpture. Some Northern Hemisphere species deposit eggs in small holes in mud under stones near the water. The female guards the eggs until they hatch. Males stridulate by rubbing the sclerotized posterior margin of the proctiger on a roughened area on the genital capsule.


    Information Sources: Andersen & Weir 2004, Cassis & Gross 1995, Lansbury & Lake 2002, Todd 1960, Gooderham & Tsyrlin 2002, Cassis & Silveira 2001
    Key to species: Andersen & Weir 2004