Ye gods, 450 already... and I have more than enough backlog to take it to 500. I should start thinking about one of those print-on-demand books.
Dindymus sp. - according to Tony/servitude on Flickr, usually put in D. versicolor, but the group is in dire need of revision, like so many Australian insects. Family Pyrrhocoridae. Harlequin Bugs, or as I've been calling them, Fire Bugs.
Found a whole swarm of these under bark in Uranquinty, near Wagga Wagga, in New South Wales. 20 years ago I got some of my best specimens from around there, so going back with a camera-phone was nice.
They fled at high speed when I disturbed them by lifting up the bark, which was odd given their warning colours.
Most Pyrrhocorids feed on plants, and some like the Cotton Stainer, are important crop pests. Others feed on decaying matter, and some are predators.