Print This Page

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


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

Descriptive Features:

  • body dorsoventrally flattened, ovoid-elliptical to broadly oval, typically blackish brown to yellowish brown and sometimes mottled
  • head transverse
  • eyes large and contiguous with the anterior margin of pronotum
  • ocelli are absent
  • antennae 4-segmented, not visible from above
  • rostrum short and stout, appearing 3-segmented
  • pronotum large, subtrapezoidal
  • scutellum large and triangular
  • forelegs enlarged, flattened and raptorial, fore femora broadly triangular
  • midleg cursorial
  • hindlegs usually modified for swimming
  • fore tarsi 1-segmented
  • mid and hind tarsi 2-segmented, with elongate claws
  • Total length: 6.2 - 9.6 mm 

    Naucoris congrex


    Naucoris sp. juvenile

    Taxonomic Checklist: Species
    Naucoris australicus Stal
    Naucoris congrex Stal
    Naucoris magela Lansbury
    Naucoris rhizomatus Polhemus
    Naucoris subaureus Lansbury
    Naucoris subopacus Montandon

    Distribution: Australia wide

    Sensitivity Rating: SIGNAL grade 2

    Functional Feeding Group: predators, scavengers


    Ryans Billabong, Albury NSW

    Ecology: Instream habitat: Naucoris typically occur in well vegetated stagnant waters or in sluggish backwaters of streams, amongst the vegetation and debris.
    Feeding ecology: Naucoris are strong predators that hide in the vegetation until prey comes along rather than chase the prey which they catch and hold with raptorial legs. They feed on molluscs (Bivalvia), small crustaceans; including water fleas (Cladocera), amphipods (Amphipoda), isopods (Isopoda), and various aquatic insects; including corixids (Hemiptera), dragonfly (Odonata), midge (Diptera: Chironomidae) and mosquito larvae (Diptera: Culicidae).
    Habit: Although they are good swimmers naucorid bugs generally crawl amongst the vegetation and debris, giving them the common name of ‘creeping bugs’. Naucoris species rely on atmospheric oxygen, having spiracles opening into a subalar air store, they return to the surface periodically to renew their air supply. Adults have wings and can quickly disperse from one water body to another.
    Life history: The biology of Australian Naucoris species is not well known. In Northern Hemisphere species, males can produce stridulatory sounds to attract females. The eggs are embedded in plant tissue under water or attached superficially to the substrate. Egg development takes about one month. There are five moults from nymph to adult, taking a further two months.


    Information Sources: Andersen & Weir 2004, Cassis & Gross 1995, Lansbury & Lake 2002, Gooderham & Tsyrlin 2002, Hawking & Smith 1997
    Key to Species: Andersen & Weir 2004