Dytiscidae (Predacious Diving Beetles)

The Predacious Diving Beetles are a large and common freshwater beetle that prey on other small organisms: both invertebrate and vertebrate.  They are commonly found toward the edges of slow moving fresh water bodies such as ponds, dams ditches, still creeks and some species can tolerate saline lakes. Adults move up to the surface to collect air which they store under their elytra.  The adults can fly to disperse to other water sources.  They are also attracted to light and can mistake shining surfaces such as glass to be a water body. Eggs of many species are laid in the split stems of underwater plants, and the larvae are voracious predators.  They crawl out of the water to pupate in damp soil.
Australia has a rich representation of Dytiscidae, divided into eight subfamilies.   29 species are listed for Tasmania.

Subfamily Hydroporinae

Tribe Hydroporini
Genus Antiporus

Genus Chostonectes 
IMG 1538

Subfamily Colymbetinae
Tribe Colymbetini
Genus Rhantus
   

    IMG 5728  IMG 1570

References

CSIRO, 1990. Insects of Australia, Volume  2: A Textbook for Students and Research Workers. 2nd Edition. Melbourne University Publishing.

CSIRO 2009, Taxon Attribute Profiles: Family Dytiscidae, CSIRO Water for a Healthy Country Flagship, Australia.

Semmens, TD; McQuillan PB and Hayhurst G 1992, Catalogue of the Insects of Tasmania, Department of Primary Industry Tasmania