Predaceous Diving Beetle Sandracottus bakewellii (Family Dytigcidae)
Published October 27, 2012 | ” A beetle not a bug. It is certainly one of the diving beetles in the family Dytigcidae, but there are a few black and yellow genera and species. This beetle could be in the genera Megaporus or Sternopriscus.” Found in the dam feeding on small aquatic organisms.
It is Sandracottus bakewellii (Clark, 1864), an endemic Dytiscidae of Australia, distributed in tropical northern Australia and along the east coast south to Brisbane.
Lars Hendrich, entomologist, Zoologische Staatssammlung, Munich, Germany
I.D courtesy of Martyn Robinson. Naturalist Australian Museum. 
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It is Sandracottus bakewellii (Clark, 1864), an endemic Dytiscidae of Australia, distributed in tropical northern Australia and along the east coast south to Brisbane.
Lars Hendrich, entomologist, Zoologische Staatssammlung, Munich, Germany