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

Gerridae

Major Group: Insecta
Order:
Hemiptera
Family:
Gerridae

Descriptive Features:

  • body elongate to ovoid, covered with several types of waterproof hairs, giving a velvety appearance, usually black or brown, occasionally with pale markings, venter is often silvery
  • head short and conical
  • eyes large and globular
  • antennae 4-segmented
  • rostrum 4-segmented
  • pronotum prominent, variable in length (apterous form) or large, pentagonal (macropterous form) 
  • wing polymorphism common, with apterous, brachypterous and macropterous forms known
  • legs are long and slender, with hind femora extending beyond the abdomen
  • tarsi 2-segmented, claws inserted preapically
  • Total length: (m) 1.8 - 20.6 mm (f) 2.0 - 17.3 mm, leg span can be more than 50 mm
  • Taxonomic Checklist: Genera
    Aquarius
    Austrobates
    Calyptobates
    Halobates
    Limnogonus
    Limnometra
    Rhagadotarsus
    Rheumatometra
    Tenagogerris
    Tenagogonus

    Distribution: Australia wide. Tenagogerris is endemic to Australia.

    Sensitivity Rating: SIGNAL grade 4

    Functional Feeding Group: predators

    Ecology: Instream habitat: Gerridae species are most diverse in tropical waters. They occur in small or large groups on the surface of ponds, lakes, and the edges of wetlands or slow-flowing rivers.
    Feeding ecology:Gerrids are active predators, feeding on aquatic insects and other invertebrates. They sense their prey using ripples on the water surface then trap it and stab it with their beak. Cannibalism is not uncommon so the juveniles stay together for safety, away from the adults. Several adult individuals, sometimes even from different species, will hunt together as a pack to capture a larger prey.
    Habit: Commonly known as ‘water striders’, gerrid bugs hold their forelegs close to their body and spread their middle and hind legs on the water surface, often giving the impression that they have only four instead of six legs. The hydrophobic hairs on their tarsi, together with their preapical claws, help them to stay on the surface film without breaking through it. Water striders have excellent eyesight and when approached within a metre or so, tend to skate away.
    Life history: Mating behaviour is complex, ranging from monogamy, when a male stays with his female protecting her from other males, to polygamy when males try to mate with as many females as possible. Sometimes males get together to display for females and the best male gets to mate more than others do. This is called polygyny. Males and females communicate by making rhythmic ripples on the water surface. A male will use ripple signals to attract a female and stimulate her when she responds, as well as to tell other males to stay away from his mate. Most females lay their eggs below the water surface on vegetation or deposit the eggs on or in floating objects. The gerrid life cycle typically has five juvenile stages. Tropical species have several or continuous generations each year. Temperate species have only one or two generations each year. The adults are usually the hibernating stage.
     
     
    Information Sources: Andersen & Weir 2004, Andersen & Weir 1998, Andersen & Weir 1997, Cassis & Gross 1995, Lansbury & Lake 2002, Gooderham & Tsyrlin 2002
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