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


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

Descriptive Features:

  • body usually elongate, parallel-sided and slender, with thread-like appendages
  • head very long, particularly in front of the eyes, with 3 pairs of cephalic trichobothria inserted in cuticular pits
  • ocelli absent
  • antennae long slender, subflagelliform, 4-segmented with ultimate segment invaginated
  • rostrum elongate, 4-segmented
  • adults with pronotum covering mesonotum in both winged and wingless forms
  • wing polymorphism common
  • forewing venation reduced with 4 or fewer closed cells
  • metathoracic scent apparatus absent
  • nymphs lack dorsal abdominal gland openings
  • tarsi 3-segmented, claws terminal
  • abdomen elongate
  • Female: ventral surface of abdominal segment 8 not modified
  • Male: ventral surface of abdominal segment 8 modified
  • Total length: 7.8 - 13.8 mm (m) 10.6 - 18.1 mm (f)

    Hydrometra strigosa


    Hydrometra strigosa, micropterous adult

    Taxonomic Checklist: Species
    Hydrometra claudie Polhemus & Lansbury
    Hydrometra darwiniana Polhemus & Lansbury
    Hydrometra feta Hale 
    Hydrometra illingworthi Hungerford & Evans
    Hydrometra jourama Polhemus & Lansbury
    Hydrometra novaehollandiae Polhemus & Lansbury
    Hydrometra orientalis Lundblad
    Hydrometra papuana Kirkaldy
    Hydrometra strigosa Skuse

    Distribution: Australia wide

    Sensitivity Rating: SIGNAL grade 3

    Functional Feeding Group: predators, scavengers 


    Murray River, Barmah Vic

    Ecology: Instream habitat: Hydrometra species are semi-aquatic bugs that occur in vegetation covered quiet waters such as permanent or temporary pools, ponds, billabongs and littoral areas of creeks and rivers. They are commonly found on the vegetation close to the water margin, only occasionally crossing large stretches of open water. These bugs are generally found in freshwater but are also known from saltwater, brackish water and from rock surfaces above the water line.
    Feeding ecology:Hydrometra bugs are predators or scavengers on dead or dying arthropods found on the water surface, typically midges (Diptera: Chironomidae), mosquito larvae (Diptera: Culicidae), bloodworms (Diptera: Chironomidae), shrimps (Decapoda) and springtails (Collembola), but are capable of spearing live invertebrates through the surface film, typically mosquito larvae (Diptera: Culicidae), cladocerans (Crustacea: Cladocera), and ostracods (Crustacea: Ostracoda). They timidly approach the prey, waving their long antennae (with specialized sense organs at the tip).The prey is speared with a long and slender rostrum and usually carried to land where every bit is sucked out.
    Habit: Hydrometra are stick-like bugs, commonly known as ‘water measurers’, referring to their slow measured movement across open water. These bugs are cryptic with their slender limbs and body allowing them to blend with the vegetation. In Northern Hemisphere observations, Hydrometra have been seen to raise and lower the body rhythmically to obscure the body outline and they also become immobile (“play dead”), when handled roughly, with antennae stretched forward and legs pressed against the body.
    Life history: The complete life history of Australian Hydrometra species is not known. Adults of the most common species, Hydrometra feta and Hydrometra strigosa, are active throughout the year with nymphs recorded from January, March-July, August, and October- December. Most Australian Hydrometra species are wing dimorphic, with macropterous forms being the most frequent adult form. Flight activity may be restricted to daylight hours as Hydrometra are not common in light trap collections. The hydrometrid egg has a multilayered shell and a distinct pedicel. Eggs are normally laid up to several centimetres above the water level, on vertical objects and attached in an upright position by its pedicel. The egg is tolerant of dry conditions. The embryo has a frontal appendage which is used to produce a longitudinal split prior to hatching.


    Information Sources: Andersen & Weir 2004, Cassis & Gross 1995, Lansbury & Lake 2002, Gooderham & Tsyrlin 2002, Ingram et al 1997
    Key to Species: Andersen & Weir 2004 (males)