Print This Page

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


Major Group: Insecta

Descriptive Features:

  • body varies from oval to elongate, covered with velvety hydrofuge hairs
  • head short and transverse with a fine groove impressed on frons and postclypeus
  • 3 pairs of cephalic trichobothria present
  • eyes usually large
  • ocelli absent
  • antennae 4-segmented
  • rostrum 4-segmented, slender, usually reaches mesosternum
  • wing polymorphism common
  • legs relatively short, coxae separated, femora moderately incrassate, tibiae with grasping combs
  • typically fore tarsi 1-segmented, mid and hind tarsi 2-segmented except for Rhagovelia where all tarsi are 3-segmented
  • pretarsi inserted preapically and have symmetrical claws, with a pair of arolia and a pair of setiform parempodia
  • Male: smaller, fore tibiae usually with grasping comb 
  • Female: larger, fore tibiae without grasping comb
  • Total length: 1.0 - 4.4 mm
  • Taxonomic Checklist: Genera

    Distribution: Tas, WA, Qld, NSW, Vic, SA, NT, ACT

    Sensitivity Rating: SIGNAL grade 3

    Functional Feeding Group: predators, scavengers

    Ecology: Instream habitat: Veliidae species are semi-aquatic and occur in quiet lotic and lentic waters with emergent vegetation. They usually dwell on the water surface of littoral areas but are also known to crawl over mudflats and wet rocks.
    Feeding ecology: Veliid bugs are predators and scavengers feeding on a variety of small crustaceans, including ostracods (Ostracoda) and water fleas (Cladocera), as well as insects such as mosquito larvae (Diptera: Culicidae). Like the larger water striders these bugs can detect their prey by vibrations on the surface of the water.
    Habit: Commonly known as ‘small water striders’, veliid bugs either walk, run or row across the water surface. In Northern Hemisphere species, a peculiar mode of locomotion has been observed that may also apply to Australian species. “Skimming” is enabled by the spread of a detergent type fluid, from the rostrum, which lowers the surface tension allowing the small water strider to propel suddenly across the water surface. This mode can be utilised for both prey capture by the veliid bug and predator avoidance from a larger bug, as the larger bug will be expelled in the opposite direction by the change in surface tension. In Australia, Veliidae species are typically found in a large aggregation which possibly lowers the risk of predation.
    Life history: Eggs are relatively small with a porous shell and two to four micropyles. Generally, the eggs are glued lengthwise to emergent or floating water plants, under water or at the water surface. The embryo has a median, clypeal egg burster which is used to produce a longitudinal split in the egg shell just prior to hatching. There are five moults from nymph to adult.
    Information Sources: Andersen & Weir 2004, Andersen & Weir 2003, Andersen & Weir 2001, Cassis & Gross 1995, Lansbury & Lake 2002, Gooderham & Tsyrlin 2002, Davis & Christidis 1997, Sloane & Norris 2002 
     More ›››  key to genera